Award type：Award from publisher, newspaper, foundation, etc.  Country：Japan

Country：Japan

Country：Netherlands

Country：Japan

Country：Japan

Country：Korea, Republic of

Country：Japan

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals  

The optimization of processing parameters is indispensable for the laser powder bed fusion (L–PBF) process. The deposited energy density (DED) is one of the process indexes for the L–PBF process and has a simplified formula of P·v−0.5, where P is the laser power, and v is the scan speed. This parameter describes the change in the relative density and the melt pool morphology with laser power and scan speed well, whereas it does not include the effect of other processing parameters, e.g., hatch spacing (S). In the present study, an attempt was made to incorporate the effect of S into DED. Al–12Si (mass%) alloy cube samples were fabricated by L–PBF under various P, v, and S, for evaluating the relative density and the melt pool morphology. The melt pool depth and width of L–PBF–manufactured Al–12Si alloy increased linearly with P·v−0.5 and did not exhibit a clear correlation with S. Based on the experimental observation, the effect of hatch spacing on DED was estimated to be S−0.5, and a new index of P·v−0.5·S−0.5 was proposed. This index described the change in the relative density of the L–PBF–manufactured Al–12Si alloy with laser conditions (P, v, and S) well when the thermal conduction mode melting was dominant. This study also indicated the limitation of the applicability of P·v−0.5·S−0.5 under the keyhole or transition mode melting.

DOI： 10.2320/jinstmet.JA202401

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Materials Research and Technology  

The present study was undertaken to understand the effect of annealing on the microstructural features of the melt-pool structure and the associated multiscale mechanical properties of the Al–2.5%Fe–2%Cu alloy manufactured by laser powder bed fusion (LPBF). Microstructural characterizations and tensile tests were conducted for the LPBF-built specimen and those subsequently annealed at various temperatures ranging from 200 to 500 °C. Nanoindentation hardness mapping was used to evaluate the mechanical inhomogeneity of the melt-pool structure and its changes by annealing at different temperatures. The LPBF-manufactured sample exhibited a melt-pool structure containing numerous particles of the Al23CuFe4 phase (oC28, orthorhombic structure) formed because of local melting and rapid solidification during the LPBF process. The relatively coarsened cellular structure localized along the melt-pool boundary resulted in local soft regions. The local vulnerability contributed to the direction dependence of the tensile ductility. A slight variation was observed in the inhomogeneous microstructure of the samples annealed at 200 or 300 °C. The formation of numerous Al23CuFe4 nanoprecipitates in the α-Al supersaturated solid solution prevented strength loss after post-heat treatments. In addition, considerable coarsening of the intermetallic phase after annealing at 500 °C eliminated the melt-pool structure. The tensile performance of the specimens demonstrated a ductile fracture mode, wherein ductile fracture occurred in the α-Al matrix with low hardness while the harder θ-Al13Fe4 stable phase was embedded within it. The anisotropy in the mechanical properties was less pronounced owing to the significant microstructural changes.

DOI： 10.1016/j.jmrt.2024.09.013

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Materials Science and Engineering: A  

Laser powder bed fusion (L-PBF) is an additive manufacturing technology widely applied to the manufacture of metallic parts. The L-PBF processed aluminum-silicon (Al–Si) cast-type alloy components exhibit an anisotropic tensile ductility. In this study, we investigated the influence of heat treatments on the microstructural features of an Al–12%Si binary alloy fabricated via L-PBF and the associated inhomogeneous deformation of its melt-pool structure, which contributes to the resulting anisotropic tensile ductility. The mechanical inhomogeneity of the melt-pool structure and the change induced by annealing at various temperatures (300 and 530 °C) were characterized using microscale digital-image correlation analyses of scanning electron microscopy images obtained in situ during tensile deformation and nanoindentation hardness mapping. In the specimen fabricated via L-PBF, the high strain was concentrated at the locally coarsened microstructure (the soft region) along the boundaries of the melt pools rather than at the refined solidification microstructure (the hard region) within the melt pools. The localized strain varied depending on the geometrical relation between the orientation of the melt-pool boundary and the tensile direction, thus contributing to the anisotropic tensile ductility. This tendency appeared less pronounced in the specimen annealed at 300 °C, which exhibited a slightly homogenized melt-pool structure. The reduced strain localization is associated with a reduced difference in local strength between the melt-pool boundary (soft region) and the melt-pool interior (hard region). The slight homogenization of the melt-pool structure emphasized the effect of grain morphologies in the α-Al matrix on the inhomogeneous deformation within melt pools. In the specimen annealed at 530 °C, which exhibited a homogenized α-Al/Si two-phase microstructure, the uniformly distributed Si phase would be responsible for the homogenous deformation, resulting in an isotropic tensile ductility. This study advances our understanding of the correlation between the melt-pool structure and the deformation behavior of Al–Si alloys processed using L-PBF, which provides new insights for controlling the ductility by post-processing.

DOI： 10.1016/j.msea.2024.146808

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Alloys and Compounds  

The addition of Mn in Al–Fe alloys stabilizes the Al6Fe metastable phase (orthorhombic structure, oC28) owing to the partial occupation of Fe sublattice sites by Mn atoms (formation of Al6(Fe, Mn) phase), thereby achieving superior high-temperature strength of Al–Fe–Mn ternary alloys that are manufactured via laser powder bed fusion (L-PBF) process. This study aimed to fundamentally understand the thermal stability of the refined Al6(Fe, Mn) phase formed in the L-PBF fabricated Al–2.5%Fe–2%Mn alloy in terms of a thermodynamic approach and the kinetics of morphological changes in the Al6(Fe, Mn) phase at elevated temperatures ranging from 200 to 500 ℃. The L-PBF processed samples showed a high hardness of approximately 125 HV due to the formation of numerous dispersoids of the Al6(Fe, Mn) phase with sizes of several tens of nanometers in the α-Al matrix containing concentrated solute elements of Fe and Mn. The hardness and microstructure were almost unchanged even after exposure to a high temperature of 200 ℃ for an extended period of 1000 h. Upon exposure to 300 ℃, nucleation and growth of the Al6(Fe, Mn) phase occurred locally, particularly at grain boundaries in the α-Al matrix. Such a local growth contributed to a reduction in hardness upon thermal exposure. Simultaneously, numerous nanoscale precipitates were formed in the α-Al matrix, resulting in a suppressed reduction in hardness. Contrary to the result of the thermodynamic calculations, the θ-Al13Fe4 phase was scarcely found even after long-term exposure to 500 ℃. The θ-phase formation was accompanied by the dissolution of the refined Al6Fe metastable phase for strengthening, which significantly reduced the hardness during thermal exposure. The suppressed θ-phase formation could be associated with the thermodynamically stable Al6(Fe, Mn) phase developed during the L-PBF process, which predominantly contributed to the high microstructural stability of the L-PBF fabricated Al–Fe–Mn alloy at elevated temperatures.

DOI： 10.1016/j.jallcom.2024.174593

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Journal of Heat and Mass Transfer  

The capillary pressure (ΔPcap) and permeability (K) of porous wicks, both of which depend on the size of the flow channel, are crucial for the performance of heat transfer devices including loop heat pipes. However, the flow channel in actual porous wicks shrinks at the connective part between adjacent pores called the throat and does not have a constant size. The dominant flow channel size (average size or throat size) for ΔPcap and K remains unclear. To elucidate the dominant flow channel size, porous aluminum with constant pore size and various throat sizes was controllably fabricated by the space holder method using sodium chloride (NaCl) particles. Two types of pore size (simple pore size reflecting the space holder size and connectivity-reflected pore size) were characterized by X-ray computed tomography. The ΔPcap and K were evaluated by capillary rise tests using water. The average simple pore size was almost constant, but the average connectivity-reflected pore size changed depending on the porosity controlled by the amount of the NaCl space holder because the throat was enlarged, and the connectivity was improved by increasing porosity. It was clarified that ΔPcap changed depending on the average connectivity-reflected pore size regardless of the constant simple pore size. In contrast, K was determined by neither the simple nor connectivity-reflected pore sizes and could be dominated by local size around the throat. These results provide an insight into the design of optimal porous structure appropriate for porous wicks applied to heat transfer applications.

DOI： 10.1016/j.ijheatmasstransfer.2024.125217

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Corrosion Science  

Four-dimensional (4D) electrochemical impedance spectroscopy was applied to clarify the role of microstructures on the corrosion behaviour of Al-Si alloys additively manufactured by laser powder bed fusion in the immersion of NaCl solution. 3D complex impedance plots, comprising real, imaginary, and time axes, indicate that the impedance increases gradually at initial stage and then does not show apparent time variation. These behaviours, following surface morphology analysis, are strongly related to the remaining fine silicon particles on the surface due to the preferential Al dissolution, which suppress the further dissolution from underlying along with the protective oxide film formation.

DOI： 10.1016/j.corsci.2024.112018

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Applied Physics Letters  

High-entropy alloys (HEAs) are a class of materials known for their unique properties, including high strength, excellent wear resistance, and good corrosion resistance. Sub-micron- and nanosized HEA particles were fabricated via pulsed laser ablation in liquid using a Cantor alloy target. The Cr20Mn20Fe20Co20Ni20 target was immersed in pure water and ablated using a focused nanosecond-pulsed Nd: YAG laser. A dark solution containing HEA particles was obtained which was stable for about one week before agglomeration and precipitation was observed. The diameters of the obtained particles ranged from several tens of nanometers to several hundred nanometers. Increasing the laser power resulted in higher particle concentration and an increase in the intensity of UV-vis absorption spectra. Electron diffraction was used to confirm that the composition of the particles was close to that of the Cantor alloy, although the concentrations of Cr and Mn were slightly deficient. There was also a weak dependence of the composition on laser power, and all the particles also contained oxygen. Selected area electron diffraction revealed that the composition varied spatially within some particles and that they are mainly polycrystalline. This work shows that HEA particles can be quickly, safely, and effectively manufactured using liquid-based laser ablation, opening the pathway for mass manufacture and disruptive applications in, e.g., catalysis or tribology.

DOI： 10.1063/5.0200341

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Materials Science and Engineering: A  

This study identifies the role of solute Cr in the thermal activation process in the plastic deformation of α-(Fe, Cr) ferrite (BCC solid solutions) using micropillar compression tests for micron-sized single-crystals fabricated on various Fe–Cr binary alloys that were solution-treated at 1573 K. Fe–18%Cr single-crystal micropillars with a mean diameter d of ∼2 μm exhibited a relatively higher strain rate sensitivity (m) of 0.12 for the stress required for slip initiation. Larger Fe–18%Cr micropillars (d = 5 μm) exhibited a lower m value of 0.04. The corresponding activation volume of 50 b3 was equivalent to the millimeter-sized pure Fe and Fe–18%Cr alloy specimens (60–70 b3), indicating the prevalence of a general mechanism involving dislocation motion (kink-pair nucleation of screw dislocations). This mechanism controls the thermal activation process of plastic deformation in the Fe–18%Cr alloy, which has sufficient sources for dislocation multiplication. In the Fe–25%Cr and Fe–40%Cr single crystal micropillars, a less pronounced size-dependent m value (0.01–0.03) was determined, almost independent of specimen size. The corresponding activation volumes of large micropillars (74–77 b3) were similar to those of millimeter-sized specimens, which indicates a mild effect of solute Cr atoms on the thermal activation process of dislocation motion in Fe–Cr binary alloys at ambient temperature. Initial dislocations, rather than Cr content in Fe–Cr binary alloys, led to the low changes in size-dependent activation volume of Fe–Cr alloys with higher Cr content. Planar faults (Cr-enriched regions) were observed in Fe–40%Cr alloys, which may become sufficient sources for dislocation nucleation. However, the influence of Cr-enriched regions on dislocation motion remains unclear.

DOI： 10.1016/j.msea.2024.146499

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Alloys and Compounds  

Al-12mass%Si binary alloy was fabricated by laser-powder bed fusion (L-PBF). The effect of low temperature annealing (LTA) less than 573 K on electrical and mechanical properties, microstructure, and residual stress of L-PBF Al-12mass%Si was investigated. Due to LTA, electrical resistivity at 77 K and 293 K changed from 34 nΩm down to 10 nΩm and from 68 nΩm down to 45 nΩm, respectively. The lattice constant of α-Al phase increased around 0.0005 nm by LTA according to X-ray diffraction. The change was associated with the decrease in the concentration of solid-solution Si of around 3.4 mass% by electrical resistivity measurement and 3 mass% by X-ray diffraction, when the annealing temperature was 473 K. Whereas, Vickers hardness increases around 145 HV compared with that for the as-built value of 141 HV, and then, decreases down to 126 HV and saturates. TEM/EDS observations confirmed the precipitation of fine Si within the α-Al phase. The decrease in annealing temperature increases the time to reach the Vickers hardness peak. 0.2% proof stress obtained by compression tests shows anisotropy, which can be attributed to the anisotropy on residual stress, which still exists after LTA.

DOI： 10.1016/j.jallcom.2024.173737

Scopus

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Materials Science and Technology  

The microstructural factors contributing to the high strength of additive-manufactured Al–Si alloys using laser-beam powder bed fusion (PBF-LB) were identified by in-situ synchrotron X-ray diffraction in tensile deformation and transmission electron microscopy. PBF-LB and heat treatment were employed to manufacture Al–12%Si binary alloy specimens with different microstructures. At an early stage of deformation prior to macroscopic yielding, stress was dominantly partitioned into the α-Al matrix, rather than the Si phase in all specimens. Highly concentrated Si solute (∼3%) in the α-Al matrix promoted the dynamic precipitation of nanoscale Si phase during loading, thereby increasing the yield strength. After macroscopic yielding, the partitioned stress in the Si phase monotonically increased in the strain-hardening regime with an increase in the dislocation density in the α-Al matrix. At a later stage of strain hardening, the flow curves of the partitioned stress in the Si phase yielded stress relaxation owing to plastic deformation. Therefore, Si-phase particles localized along the cell walls in the cellular-solidified microstructure play a significant role in dislocation obstacles for strain hardening. Compared with the results of the heat-treated specimens with different microstructural factors, the dominant strengthening factors of PBF-LB manufactured Al–Si alloys were discussed.

DOI： 10.1016/j.jmst.2023.08.050

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Alloys and Compounds  

This study proposes a design concept for an Al-Si-Mg ternary alloy to achieve both high strength and laser-based powder bed fusion (PBF-LB) processability using calculation of phase diagrams (CALPHAD). The thermodynamic calculations using the CALPHAD method evaluated the Al-10Si-4.5Mg (wt%) alloy composition for strengthening by both the Si and Mg2Si phases and high PBF processability by reducing the risk of hot tearing behind the small freezing range of 27 °C and crack susceptibility index (|dT/d(Fs1/2)|) of 77 °C. The PBF-LB Al-10Si-4.5Mg alloy sample (processed by laser power of 128 W and laser scanning velocity of 1000 mm/s) exhibited a fine three-phase microstructure and exceptional hardness of 199 HV. No hot tearing occurred, whereas many cracks preferentially propagated along the melt pool boundaries during the PBF-LB process. The severe lateral cracking resulted in a maximum relative density of 96 % in the Al-10Si-4.5Mg alloy samples. Preferential cracking could be responsible for the localization of the relatively coarse particles of the brittle Mg2Si phase in the cellular microstructures of the melt pool boundaries. Understanding the lateral cracking mechanism can provide new insights into alloy modification using the controlled solidification path to avoid a specific two-phase eutectic reaction (L→α-Al+Mg2Si) to improve the PBF processability. A modified alloy composition of Al-10Si-3Mg (wt%) was assessed using the CALPHAD approach. PBF-LB processing using the modified alloy powder alleviated cracking and improved the maximum relative density to 98 % for the PBF-LB manufactured samples. This result accentuated the validity of the design strategy for Al-Si-Mg ternary alloy utilizing the CALPHAD method.

DOI： 10.1016/j.jallcom.2024.173449

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Materials Research and Technology  

To understand the microstructural factors controlling deformability during the forming process, a comprehensive analysis using in-situ scanning electron microscopy (SEM) with digital image correlation (DIC) for hot-dip Zn–6 %Al–3 %Mg alloy coatings on steel sheets in bending deformation was performed. The Zn–Al–Mg alloy coating exhibited two major microstructural constituents: the primary solidified Al (fcc) phase with dendritic morphologies and a fine ternary eutectic (TE) microstructure of the Zn (hcp), Al, and Zn2Mg phases. Major cracks were initiated on the tensile-strained coating surface, where the strain was localized in the TE regions, whereas the softer dendritic Al phases prevented the crack propagation. Microcracks were initiated in the binary eutectic (BE) Zn/Zn2Mg phases (Al-poor region) localized around the dendritic Al phases, whereas they were arrested in the TE region containing fine granular Al phases. The dendritic Al and fine granular Al phases embedded in the TE microstructure contributed to the high crack resistance.

DOI： 10.1016/j.jmrt.2024.01.235

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Additive Manufacturing Letters  

Laser-beam powder bed fusion (PBF-LB) technique was used to produce an Al–2.5 %Fe–2 %Cu ternary alloy, featuring a two-phase eutectic composition of α-Al/Al23CuFe4 in non-equilibrium solidification, as determined by thermodynamic calculations. The specimen manufactured by PBF-LB exhibited a high tensile strength exceeding 350 MPa and a low thermal conductivity of approximately 140 W m−1 K−1. Subsequent annealing at 300 °C improved the thermal conductivity to 175 W m−1 K−1 without compromising the strength. This improvement was attributable to forming numerous Al23CuFe4 nanoprecipitates, which consumed solute elements. By appropriately managing the factors contributing to strengthening, a superior strength–conductivity balance can be achieved by implementing post-heat treatments.

DOI： 10.1016/j.addlet.2023.100191

Scopus

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Materials Science and Engineering: A  

This study aims to fundamentally understand the effect of 0.1 at% Ti addition (for introducing solute Ti with low diffusivity into the α-Al matrix) on the microstructure and high-temperature mechanical performance of a heat-resistant Al–5Mg–3.5Zn–2Cu–2Ni (at.%) quinary alloy subjected to heat treatments. The precipitation morphologies of the T-Al6Mg11Zn11 phase are systematically characterized in terms of the distribution of solute Ti, which is controlled by a peritectic reaction during solidification. High-temperature strength and creep properties (200 °C/105 MPa) are examined using the Ti-added alloy specimen and compared with the results of Ti-free quinary alloy specimens. In the Ti-added alloy, solute Ti is distributed within the dendritic α-Al phases formed through the peritectic reaction. The precipitation morphologies vary depending on solute Ti contents in the α-Al matrix after isothermal aging at 200 and 300 °C. Numerous fine T-phase precipitates are homogeneously dispersed in the α-Al matrix containing high solute Ti content. Fine precipitation morphologies appear stable even after long-term exposure at 200 °C. Ti addition extends creep rupture life (at 200 °C) without the loss of static high-temperature strength and room-temperature ductility. The improved creep properties could be responsible for the reduction in creep rate by the refined precipitation morphologies in the α-Al matrix containing higher solute Ti contents. Local coarsening of the precipitates occurs owing to the solute Ti during creep (under stress). The mechanism is discussed in terms of the effect of Ti addition on the phase equilibria between the α-Al and other intermetallic phases.

DOI： 10.1016/j.msea.2023.145859

Scopus

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ISIJ International  

This study was set to fundamentally investigate the characteristics of austenite reversion occurring in maraging steels additive-manufactured by laser powder bed fusion (L-PBF). The maraging steel samples manufactured under different L-PBF process conditions (laser power P and scan speed v) were subjected to heat treatments at 550°C for various durations, compared with the results of the austenitized and water-quenched sample with fully martensite structure. The L-PBF manufactured samples exhibited the martensite structure (including localized austenite (γ) phases) containing submicron-sized cellular structures. Enriched alloy elements were detected along the cell boundaries, whereas such cellar structure was not found in the water-quenched sample. The localized alloy elements can be rationalized by the continuous variations in the γ-phase composition in solidification during the L-PBF process. The precipitation of nanoscale intermetallic phases and the following austenitic reversion occurred in all of the experimental samples. The L-PBF manufactured samples exhibited faster kinetics of the precipitation and austenite reversion than the water-quenched sample at elevated temperatures. The kinetics changed depending on the L-PBF process condition. The enriched Ni element (for stabilizing γ phase) localized at cell boundaries would play a role in the nucleation site for the formation of γ phase at 550°C, resulting in enhanced austenite reversion in the L-PBF manufactured samples. The variation in the reaction kinetics depending on the L-PBF condition would be due to the varied thermal profiles of the manufactured samples by consecutive scanning laser irradiation operated under different P and v values.

DOI： 10.2355/isijinternational.ISIJINT-2023-045

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Materials Transactions  

The combustion foaming process enables the fabrication of closed-cell porous intermetallics by utilizing the combustion reactions generating a large amount of heat. A closed-cell porous Al3Ti (D022 crystal structure) fabricated by the combustion foaming process has a lightweight, high stiffness, high melting temperature, and good oxidation resistance but exhibits brittleness due to the poor deformability of Al3Ti. It is known that the addition of third elements (X = Cr, Mn, Fe, etc.) changes the crystal structures from D022 to L12, resulting in an improvement in the deformability in the case of dense materials. In the present study, an attempt was made to fabricate the closed-cell porous (Al, Fe)3Ti with an L12-ordered crystal structure through the combustion foaming. The effect of the amount of the exothermic agent, which was added to control the reaction heat of combustion foaming, on the porosity, pore morphology, microstructure, and constituent phases was investigated. The closed-cell porous L12-(Al, Fe)3Ti without any intermediate phases was successfully fabricated when the exothermic agent was added over 5 vol%. The porosity reached the maximum at approximately 80% when the exothermic agent of 10 vol% was added. The TiB2 particles, which were formed by the reactions of the exothermic agent, were aggregated in the porous sample with the exothermic agent of 5 vol% but uniformly dispersed in the porous samples foamed with the exothermic agent over 10 vol%. Based on the results above and the temperature measurements during the combustion foaming, it is important for fabricating highly porous L12-(Al, Fe)3Ti with the uniform microstructure to control the maximum temperature just above the liquidus temperature of (Al, Fe)3Ti. This study provides new insights into the hierarchical control of porous materials with the desired pore structures and cell wall materials.

DOI： 10.2320/matertrans.MT-M2023213

Web of Science

Scopus

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Corrosion Science and Technology  

An attempt was made to apply digital image correlation (DIC) strain analysis to in-situ scanning electron microscopy (SEM) observations of bending deformation to quantify local strain distribution inside a ZnMgAl-alloy coating in deformation. Interstitial-free steel sheets were hot-dipped in a Zn-3Mg-6Al (mass%) alloy melt at 400 oC for 2 s. The specimens were deformed using a miniature-sized 4-point bending test machine inside the SEM chamber. The observed in situ SEM images were used for DIC strain analysis. The hot-dip ZnMgAl-alloy coating exhibited a solidification microstructure composed of a three-phase eutectic of fine Al (fcc), Zn (hcp), and Zn2Mg phases surrounding the primary solidified Al phases. The relatively coarsened Zn2Mg phases were locally observed inside the ZnMgAl-alloy coating. The DIC strain analysis revealed that the strain was localized in the primary solidified Al phases and fine eutectic microstructure around the Zn2Mg phase. The results indicated high deformability of the multi-phase microstructure of the ZnMgAl-alloy coating.

DOI： 10.14773/cst.2024.23.2.113

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ISIJ International  

The effect of Mn on the alloying reaction during hot-dip galvanization was investigated. The microstructure of the Fe–Zn intermetallic layers consisted of ζ, δ, and Γ phases for both pure Fe and Fe–2Mn (wt.%) alloy. The intermetallic layers grew thicker with increasing dipping time, and the growth rate of each layer was similar for both substrates. In the case of Fe–2Mn, the formation of the δ1p phase was observed after dipping for 2 s. However, δ1p formation was delayed for pure Fe, indicating that Mn may promote nucleation of the δ1p phase. It is known that the δ1p phase nucleates in the Fe-saturated ζ phase. The Fe content at the ζ/δ1p interface was found to be lower for the Fe–2Mn alloy by electron probe microanalysis, suggesting that the supersaturation of Fe for the nucleation of δ1p is decreased by Mn addition and Mn may stabilize the δ1p phase. Once δ1p became a continuous layer, the growth rates of the δ1p layer on pure Fe and Fe–2Mn were similar. Mn could affect only the nucleation of δ1p during the initial stage of the alloying reaction.

DOI： 10.2355/isijinternational.ISIJINT-2024-096

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Alloys and Compounds  

Wetting and interfacial reactions between molten Al and carbon fibers (CFs) are crucial for the fabrication of high-thermal conductive Al/CF composites through liquid-state processes including casting. The formation of Al4C3 which has a low thermal conductivity and high reactivity with water needs to be suppressed while improving wettability. The addition of Ti into molten Al forms TiC and contributes to significant improvement in wettability. To control a thin morphology of TiC, the kinetics of reactive wetting need to be clarified. In the present study, the reactive wetting kinetics between molten Al or Al-Ti alloy and pitch-based CF were investigated using the dipping coverage method combined with microstructural observations. The addition of Ti into molten Al drastically accelerated the wetting and reduced the apparent activation barrier for reactive wetting, which was related to the change in the interfacial products from the Al4C3 phase to the TiC phase. The Al4C3 phase grew while eroding the CFs, whereas the TiC phase formed in a thin-layered morphology around CFs and suppressed the diameter reduction of CF. The reduction in the apparent activation barrier and the morphology of carbides indicated a change in the dominant phenomena for reactive wetting from Al4C3 growth to TiC formation (controlled by diffusion in liquid Al). Based on the kinetics evaluations, CF were hybridized with pure Al and Al-Ti alloy through a casting process, and their thermal conductivities were evaluated. The addition of CF into pure Al degraded the thermal conductivity due to the eroded CF and coarsened Al4C3 phase, whereas the addition of CF into Al-Ti alloy enhanced the thermal conductivity. This study provides new insights into reactive wetting phenomena related to the fabrication of high-thermal conductive metal matrix composites.

DOI： 10.1016/j.jallcom.2023.172168

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Tribology International  

The production of an aluminum alloy using the laser powder bed fusion (LPBF) process results in a unique microstructure that differs from that of the same alloy when cast; this microstructure is advantageous for wear resistance. This study compared the wear resistance of Al-12Si and Al-2.5Fe (mass%) binary alloys produced by LPBF process with their cast equivalents, to analyze their suitability for lightweight wear-resistant parts. The wear resistance of the LPBF-produced alloys was significantly improved owing to the increase in hardness induced by the rapid cooling rate of the LPBF process and the dense dispersion of the fine secondary phase. Thus, Al alloys fabricated using LPBF can provide excellent wear resistance and possess the potential for application as industrial materials.

DOI： 10.1016/j.triboint.2023.108769

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Intermetallics  

Prealloyed Fe3Al was successfully manufactured by laser powder bed fusion. The best set of process parameters led to parts with a relative density of 99.5 %, a surface roughness, Sa, of 31.5 ± 5.6 μm and a hardness of 319 ± 14 HV0.1. Its microstructure as well as its mechanical properties at room and high temperatures were analyzed. The results of the chemical composition showed minor variations in aluminum content oscillating between 21 and 28 at.% along the melt pool. Additionally, elongated grains were observed to grow parallel to the building direction, as well as the development of a weak {001} texture along the building direction. The mechanical properties were influenced by the temperature. Compression tests showed a loss in strength with the increase in temperature, from a yield strength of 621 ± 40 MPa at room temperature to 89 ± 20 MPa at 650 °C. Reciprocating sliding wear tests showed that fragmentation of the intermetallic at room temperature occurs, whereas plastic deformation dominated at higher temperatures. For all temperatures, tribochemical wear was also present due to the oxidation of wear debris.

DOI： 10.1016/j.intermet.2023.107849

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Materials Science and Engineering: A  

The AlSi10Mg sample was additive-manufactured using laser powder bed fusion (L-PBF), and subsequent low-temperature annealing (LTA) at 413K or 473 K was applied. Vickers hardness tests show the peak at around 160 HV by 473 K annealing and around 145 HV by 413 K annealing. The flow stress of tensile and compression deformations are also affected by LTA, and peak aging condition gives the highest 0.2% proof stress. 0.2% proof stress obtained by tensile tests is around 270 MPa, whereas that obtained by compression tests is between 326 MPa and 386 MPa. Electrical resistivity at 293 K changes from approximately 80 nΩm down to around 60 nΩm, whereas that at 77 K changes from around 40 nΩm down to around 20 nΩm. The estimated concentration of solute Si in the as-built specimen is between 2.5 mass% and 2.9 mass%, corresponding to the previous results using energy-dispersive X-ray spectroscopy. The lattice constant obtained from XRD increased from 0.4043 nm up to 0.4048 nm by LTA. Both electrical resistivity and XRD measurement indicate a decrease in the concentration of solute atoms. Microstructure observations revealed numerous nano-sized precipitates of Si phase with a plate-like or granular morphologies in α-Al grains due to LTA.

DOI： 10.1016/j.msea.2023.144876

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Additive Manufacturing  

This paper presents a novel design concept for Al alloys with both sufficient laser powder bed fusion (L-PBF) processability and high-temperature mechanical performance using an Al–Fe–Mn ternary alloy with a refined α-Al/Al6M (M = Fe, Mn) two-phase microstructure. The near-eutectic (liquid → α-Al(fcc) + Al6M) composition of Al–2.5Fe–2Mn (mass%) was designed to avoid the formation of coarse primary intermetallics (having a detrimental effect on the PBF processability for densification) based on non-equilibrium liquidus projection thermodynamic calculations. The designed Al–2.5Fe–2Mn alloy powder exhibited sufficient L-PBF processability, and fully dense centimeter-sized samples (relative densities of above 99%) were successfully prepared. The L-PBF Al–2.5Fe–2Mn alloy samples exhibited a significantly refined solidification microstructure consisting of Al6M and α-Al phases in the melt-pool regions. Fe and Mn alloying elements contributed to the formation of nanoscale Al6M-phase particles and a high solid solution concentration in the α-Al matrix. The strength of the L-PBF Al–2.5Fe–2Mn alloy was slightly reduced at higher temperatures, but remained above 240 MPa at an elevated temperature of 300 °C. This superior high-temperature mechanical performance was attributed to the high thermal stability of the refined α-Al/Al6M two-phase microstructure and the formation of nanosized Al6M-phase precipitates.

DOI： 10.1016/j.addma.2023.103524

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Scripta Materialia  

Aluminum alloys fabricated by laser powder bed fusion (L-PBF) exhibit anisotropic tensile ductility. To identify microstructural origins in melt-pool (MP) structures (formed by the L-PBF process) contributing to the anisotropic ductility, the local strain distribution inside the MP structure in deformation was quantified by a combination of digital image correlation (DIC) strain analysis and in-situ SEM observations of tensile tests. It was found that higher strain was localized in locally coarsened microstructures (softer regions) along melt-pool boundaries (MPBs). The strain localization played a significant role in crack initiation (and propagation) around MPBs, contributing to fracture. The strain localization at MPBs changed depending on the geometrical relation of the MPBs with the loading direction (LD), which was controlled by the LD with respect to the building direction of L-PBF samples. The three-dimensional MPB distribution related to the LD would be responsible for the anisotropic ductility.

DOI： 10.1016/j.scriptamat.2022.115259

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Materials Transactions  

In order to investigate the effects of Mn and Cu additions on solidification microstructure and high-temperature strength of cast AlFe alloys, we have fabricated various AlFe-based alloys with compositions of Al1%Fe, Al1%Fe1%Mn, Al1%Fe1%Cu, and Al1%Fe1%Cu1%Mn (mol%) solidified at different cooling rates (0.3 K·s11 and 145 K·s11). In the Al1%Fe binary alloy, the coarsened ª-Al13Fe4 phase with a needle-shaped morphology was often observed in the furnace-cooled sample (0.3 K·s11), whereas the cast sample (145 K·s11) exhibited several elongated ¡ phases surrounded by fine ¡/Al6Fe eutectic microstructure. Such a solidification microstructure was observed in the cast Al1%Fe1%Cu alloy, whereas the Al23CuFe4 phase was locally formed in the finally solidified zone in the furnace-cooled sample. In the Al1%Fe1%Mn alloy, the Al6(Fe, Mn) phase was formed regardless of the cooling rate. Finer ¡/Al6(Fe, Mn) two-phase eutectic microstructure was almost entirely occupied in the cast sample. The fine eutectic microstructure was observed in the cast Al1%Fe1%Cu1%Mn alloy as well. Compression tests for cast alloy specimens revealed that the Al1%Fe1%Cu1%Mn alloy exhibited the highest strength level among the studied alloy specimens, indicating the combined addition of Mn and Cu elements could be effective in improving the high-temperature strength of the cast AlFe alloys.

DOI： 10.2320/matertrans.MT-LA2022010

Scopus

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan  

This study was set to fundamentally investigate the characteristics of austenite reversion occurring in maraging steels additive-manufactured by laser powder bed fusion (L-PBF). The maraging steel samples manufactured under different L-PBF process conditions (laser power P and scan speed v) were subjected to heat treatments at 550°C for various durations, compared with the results of the austenitized and water-quenched sample with fully martensite structure. The L-PBF manufactured samples exhibited the martensite structure (including localized austenite (γ) phases) containing submicron-sized cellular structures. Enriched alloy elements were detected along the cell boundaries, whereas such cellar structure was not found in the water-quenched sample. The localized alloy elements can be rationalized by the continuous variations in the γ-phase composition in solidification during the L-PBF process. The precipitation of nanoscale intermetallic phases and the following austenitic reversion occurred in all of the experimental samples. The L-PBF manufactured samples exhibited faster kinetics of the precipitation and austenite reversion than the water-quenched sample at elevated temperatures. The kinetics changed depending on the L-PBF process condition. The enriched Ni element (for stabilizing γ phase) localized at cell boundaries would play a role in the nucleation site for the formation of γ phase at 550°C, resulting in the enhanced austenite reversion in the L-PBF manufactured samples. The variation in the reaction kinetics depending on the L-PBF condition would be due to the varied thermal profiles of the manufactured samples by consecutive scanning laser irradiation operated under different P and v values.

DOI： 10.2355/tetsutohagane.TETSU-2022-066

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Materials Transactions  

The optimization of processing parameters is indispensable for the laser powder bed fusion (L-PBF) process. The deposited energy density (DED) is one of the process indexes for the L-PBF process and has a simplified formula of P v 0.5, where P is the laser power, and v is the scan speed. This parameter describes the change in the relative density and the melt pool morphology with laser power and scan speed well, whereas it does not include the effect of other processing parameters, e.g., hatch spacing (S). In the present study, an attempt was made to incorporate the effect of S into DED. Al12Si (mass%) alloy cube samples were fabricated by L-PBF under various P, v, and S, for evaluating the relative density and the melt pool morphology. The melt pool depth and width of L-PBF-manufactured Al12Si alloy increased linearly with P v 0.5 and did not exhibit a clear correlation with S. Based on the experimental observation, the effect of hatch spacing on DED was estimated to be S 0.5, and a new index of P v 0.5 S 0.5 was proposed. This index described the change in the relative density of the L-PBF-manufactured Al12Si alloy with laser conditions (P, v, and S) well when the thermal conduction mode melting was dominant. This study also indicated the limitation of the applicability of P v 0.5 S 0.5 under the keyhole or transition mode melting.

DOI： 10.2320/matertrans.MT-ME2022002

Scopus

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Keikinzoku/Journal of Japan Institute of Light Metals  

The present study investigated the effect of trace titanium (Ti) addition on high-temperature creep properties of a heat-resistant quinary aluminum (Al) alloy, with a composition of Al-5Mg-3.5Zn-2Cu-2Ni (mol%). Both the quinary alloy and Ti-added alloy were solution-treated at 480°C and then aged at 200°C for 10 hours. The creep tests were conducted at 200°C under 105 MPa. The addition of trace Ti element reduced the minimum creep rate and delayed the onset of the tertiary creep stage (creep acceleration), resulting in the extended creep rupture life of the Al-5Mg-3.5Zn-2Cu-2Ni quinary alloy. The creep rupture life of the Ti-added alloy was higher than that of the A7075 alloy but lower than that of the A2618 alloy, whereas the initial creep rate (up to 0.2% in strain) of the Ti-added quinary alloy was lower than that of the A2618 alloy. The superior creep properties were presumably due to the enhanced stability of the fine precipitation morphologies of the T-Al6Mg11Zn11 phase by solute Ti inside the α-Al matrix.

DOI： 10.2464/jilm.73.260

Scopus

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Materials Transactions  

In order to understand the influence of dislocation substructures on the size-dependent strength (smaller is stronger) of micron-sized metals, we have fabricated single-crystal cylindrical micropillars with various diameters approximately ranging from 1 to 10µm, which were prepared on the surface of the fully annealed sample and the subsequently cold-rolled samples of high-purity aluminum (Al). The annealed micropillars exhibited a size dependence of the resolved shear stress required for slip. The shear stress (¸i) normalized by shear modulus (G) and the specimen diameter (d) normalized by Burgers vector (b) followed the correlation of ¸i/G = 0.33(d/b)10.63. The size-dependent strength was reduced by cold-rolling, resulting in lower power-law exponents (0.2630.31) for the correlation in the cold-rolled specimens. The fine dislocation substructures introduced by the cold-rolling could be associated with the reduced size-dependent strength, which can be rationalized using the stochastic model of the dislocation source length in an assumption of homogenously distributed dislocations existing in the experimental micropillars. The inhomogeneous dislocation substructure with various dislocation cell sizes would contribute to a variation in the measured strength depending on the location, likely due to the probability of exiting the dislocation cell walls (local variation in dislocation density) in the micropillars fabricated on the cold-rolled Al samples. [doi:10.2320/matertrans.MT-L2023004]

DOI： 10.2320/matertrans.MT-L2023004

Scopus

Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Keikinzoku/Journal of Japan Institute of Light Metals  

In this study, we aim to address the dominant microstructural parameter of the high strength of Al-Fe alloy components additive-manufactured by the laser powder bed fusion (L-PBF) process. This study systematically investigated the compression response of single-crystal micropillars with a fixed diameter of approximately 3 μm prepared on the surfaces of the L-PBF built Al-2.5%Fe binary alloy sample, and the subsequently heat-treated samples (300°C and 500°C), together with the slowly solidified Al-2.5%Fe alloy sample for comparison. The single-crystal micropillars of the L-PBF built sample exhibited a high yield strength of approximately 250 MPa and pronounced strain hardening. The compressed single-crystal specimens exhibited a uniform deformation indicating the activated multi-slip systems. Such a trend was observed in the 300°C heat-treated sample. However, the relatively low yield strength and strain hardening rate were found in single-crystal micropillars of the 500°C heat-treated sample as well as the slowly solidified sample. In the compressed micropillars, a single-slip system was dominantly activated. These results indicated that numerous nano-sized Al 6Fe-phase particles (contained in the specimens of the L-PBF built sample and the 300°C heat-treated sample) could contribute to high yield strength and the enhanced activation of multi-slip systems resulting in the pronounced strain hardening.

DOI： 10.2464/jilm.73.523

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Materials Science and Engineering: A  

Owing to good formability, wrought Al alloys are used in a wide range of industries, including turbochargers in automobile engines. The development of Al alloys with increased high-temperature strength is necessary to improve the fuel efficiency of engines. In this study, a modified heat-resistant Al–Mg–Zn–Cu–Ni quinary alloy with superior high-temperature strength and creep rupture life at 200 °C (potential temperature in service for compressor radial impellers) was designed. The thermodynamic assessments provided a modified alloy composition of Al–5Mg–3.5Zn–2Cu–2Ni (at %) exhibiting α-Al phase in equilibrium with T-Al6Mg11Zn11 and Al3(Ni, Cu)2 phases at elevated temperatures. The experimental alloy showed granular T and Al3(Ni, Cu)2 phases often located on grain boundaries in the α-Al matrix, although the undissolved Al3Ni phase (formed in solidification) locally remained. Apart from the T phase, the η-Zn2Mg phase containing Cu element preferentially precipitated on grain boundaries. A large number of fine precipitates were dispersed homogeneously in the grain interior after the aging at 200 °C or 300 °C. Compared to the base alloy with a ternary composition of Al–5Mg–3.5Zn (at %) and conventional Al alloys, the designed quinary alloy (pre-aged at 200 °C for 10 h) showed a high strength at elevated temperatures above 200 °C. The creep-rupture life at 200 °C/105 MPa was remarkably extended to 665 h by the addition of Cu and Ni elements into the base ternary alloy. The rupture life was more than ten times longer than one (57 h) of the ternary alloys. The alloy modification based on the thermodynamic calculations provides an effective approach for designing lightweight Al alloys with superior high-temperature strength and creep rupture life.

DOI： 10.1016/j.msea.2022.144055

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Materials Science and Engineering: A  

The aim of the present study was to identify the effect of solute Ni element on the plastic deformation and its thermal activation process of 18Cr ferritic stainless steels. Single-crystal micropillars with different diameters of approximately 2 and 5 μm were fabricated on the surface of Fe–18%Cr–Ni alloy sheets containing different contents of Ni (0–2 mass%). Compression tests were performed on the micropillars at different initial strain rates to investigate the strain rate sensitivity (m) of stress for the slip initiation and the specimen-size dependence of the m value. In micropillars with a small diameter of 2 μm, the Fe–18%Cr binary alloy specimen exhibited a relatively higher strain-rate sensitivity of initial slip stress (m = 0.12), whereas m was reduced to 0.01 by adding 2% Ni. The same trend was observed in micropillars with a larger size of approximately 5 μm. The experimental results were utilized to evaluate the activation volume of plastic deformation. The activation volumes of the Fe–18%Cr alloy and alloy containing 1% Ni followed the specimen-size dependence trend of activation volume in bcc metals; however, the alloy containing 2% Ni exhibited larger activation volumes, suggesting a different thermal activation process presumably due to the significant interaction that occurred between dislocations and solute Ni atoms in bcc solid-solutions.

DOI： 10.1016/j.msea.2022.144076

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Additive Manufacturing  

A Single laser scan was performed on a sintered WC/Co composite and the process conditions were optimized to realize a WC/Co two-phase microstructure in a WC/Co composite fabricated by laser powder bed fusion (L-PBF). Laser irradiation on the sintered WC/Co composites generated two different microstructural regions. One is composed of WC and Co phases (WC/Co two-phase region), and the other includes W2C and W3Co3C phases (WC decomposition region). In the L-PBF-fabricated WC/Co composites, these two microstructural regions are distributed in a complex manner and their fractions varies depending on the laser parameters. Using a convolutional neural network model that is trained with the micrographs of single-laser-scanned WC/Co composites, the fractions of the two microstructural regions in the WC/Co composites fabricated by the L-PBF under various laser conditions were quantified. Multiple linear regression analyses revealed that the laser power and spot size contribute more than the scan speed, which has been verified by numerical analysis based on the moving heat source model. A support vector machine (SVM) suggested that low laser power and low scan speed are required for suppressing the WC decomposition in the consolidated samples. The WC decomposition has been successfully suppressed in the samples fabricated under SVM-recommended conditions.

DOI： 10.1016/j.addma.2022.103089

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Materials Science and Engineering: A  

Achieving both high strength and ductility is challenging in additive manufacturing of Al alloys using the laser powder bed fusion (L-PBF) process by altering the laser conditions to control the microstructural characteristics. The current work focuses on the influence of varying laser energy density (ED), which is adjusted by different sets of laser power (P) and scan speed (v), on the microstructure-tensile property relationships of the L-PBF-fabricated Al–2.5%Fe alloy under varying laser conditions (P = 204–230 W, v = 450–600 mm/s) with a fixed powder layer thickness (t = 30 μm) and hatch distance (h = 30 μm). With increasing ED (= P/v·t·h), a slight increase in the average size of the columnar α-Al grains was found in the experimental samples concurrently with a higher fraction of <001>-oriented grains. Nanosized particles of the Al6Fe phase with an increased tendency to interconnect were observed in the matrix inside the melt pool, and the θ phase formed within the submicron-sized cellular structure along the melt pool boundaries (MPBs). A low tensile ductility, induced by the local microstructural inhomogeneities across MPBs, was found in all specimens tensile-deformed along the building direction, which was characterized by a preference fracture along the MPBs. At higher applied ED, the tensile ductility of the experimental Al–2.5Fe alloy was significantly improved with only a slight decrease in tensile strength. The difference in concentration of Fe across the MPBs in the matrix was also moderately diminished, which is consistent with the reduced local difference in microhardness across the MPBs under higher ED conditions. Therefore, the present results demonstrate that local microstructural inhomogeneities across MPBs can be controlled by the laser conditions, thereby producing both high strength and good ductility in the L-PBF processed Al–Fe alloys.

DOI： 10.1016/j.msea.2022.143893

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Materials Processing Technology  

An Al alloy (A5052) sheet was joined with a carbon fiber-reinforced thermoplastic (CFRTP) sheet by hot pressing without melting the CFRTP sheet (that is, solid-state joining). A micro-structure was manufactured via laser irradiation of Al-Ti-C powders bedded on the A5052 sheet. The laser irradiation to Al-Ti-C powders generates numerous particle-shaped protrusions additively on the A5052 sheet, which facilitate the infiltration of CFRTP and mechanically interlock with the CFRTP sheet. To determine the optimal conditions for joining A5052 and CFRTP consisting of a polyamide 6 (PA6) matrix, the effects of joining temperature during hot pressing on the interfacial structure and joint strength were investigated. The maximum joint strength was attained at the joining temperature of 210 °C. At lower temperatures, PA6 was not sufficiently softened to infiltrate the micro-structure, resulting in lower joint strengths. At higher temperatures, carbon fibers (CFs) were exposed on the CFRTP surface and inhibited the penetration of PA6 and CFs into the micro-structure, thereby lowering the joint strength. To infiltrate PA6 and CFs into the micro-structure, hot pressing was performed in a gradient temperature field. The proposed process enabled appropriate infiltration of CFs and PA6 into the micro-structure and led to high and stable joint strength. It is expected that using the additively manufactured micro-structure approach proposed herein, the operating windows of various cutting-edge joining processes can be expanded to more moderate and lower energy conditions.

DOI： 10.1016/j.jmatprotec.2022.117629

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Materials  

The samples of the Al–15Fe (mass%) binary alloy that were additively manufactured by laser powder bed fusion (L-PBF) were exposed to intermediate temperatures (300 and 500◦C), and the thermally induced variations in their microstructural characteristics were investigated. The L-PBF-manufactured sample was found to have a microstructure comprising a stable θ-Al13Fe4 phase localized around melt-pool boundaries and several spherical metastable Al6Fe-phase particles surrounded by a nanoscale α-Al/Al6Fe cellular structure in the melt pools. The morphology of the θ phase remained almost unchanged even after 1000 h of exposure at 300◦C. Moreover, the nanoscale α-Al/Al6Fe cellular structure dissolved in the α-Al matrix; this was followed by the growth (and nucleation) of the spherical Al6Fe-phase particles and the precipitation of the θ phase. Numerous equiaxed grains were formed in the α-Al matrix during the thermal exposure, which led to the formation of a relatively homogenous microstructure. The variations in these microstructural characteristics were more pronounced at the higher investigated temperature of 500◦C.

DOI： 10.3390/ma15134497

Web of Science

Scopus

PubMed

Other Link： https://www.mdpi.com/1996-1944/15/13/4497

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Materials and Design  

We examined the variation in the solidification microstructure of AlSi10Mg alloy powder over a wide range of cooling rates controlled by using the fast scanning calorimetry (FSC) technique. Two exothermic peaks derived from the primary solidification of the α-Al phases and the α-Al/Si eutectic reaction were detected. These exothermic peaks became broader and shifted to lower temperatures at higher cooling rates. Focus ion beam (FIB) milling enables microstructural characterization of AlSi10Mg powder solidified at controlled cooling rates above 102 °C·s−1 in the FSC equipment. The sample solidified at 4 × 104 °C·s−1 exhibited a fine microstructure consisting of a primary α-Al phase surrounded by lamellar-shaped Si phases. The fraction of the Si phase continuously decreased with increasing cooling rate, indicating higher content of solute Si element in the α-Al phase solidified at a higher cooling rate. The secondary dendrite arm spacing (λ) of the primary α-Al phase decreased in the sample solidified at a higher cooling rate (dT/dt). The relation follows a general equation of λ = A (dT/dt)-n (A: 38.4, n: 0.33) in wide range of cooling rate (10-1 ∼ 104 °C·s−1). The results were utilized to discuss the cooling rate of Al alloys during the laser powder bed fusion (L-PBF) process.

DOI： 10.1016/j.matdes.2022.110830

Scopus

Other Link： https://www.sciencedirect.com/science/article/pii/S026412752200452X

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2464/jilm.72.246

Scopus

Other Link： https://www.jstage.jst.go.jp/article/jilm/72/5/72_7205-T14/_article/-char/ja/

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2464/jilm.72.178

Scopus

Other Link： https://www.jstage.jst.go.jp/article/jilm/72/5/72_7205-T08/_article/-char/ja/

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2464/jilm.72.164

Scopus

Other Link： https://www.jstage.jst.go.jp/article/jilm/72/5/72_7205-T06/_article/-char/ja/

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Scripta Materialia  

This article reports an unexpected finding of the mechanical behavior of Al-12%Si alloy manufactured using the laser powder bed fusion (L-PBF) process. The as-manufactured specimen has a negative strain rate sensitivity of flow stress at an early stage of tensile deformation (below 3% in strain). The post heat-treated specimens exhibited a positive strain-rate sensitivity and none of these specimens exhibited a serrated stress-strain curve, indicating a mechanism different from the Portevin–LeChatelier effect. Transmission electron microscopy revealed the dynamic precipitation of the nano-sized Si-phase inside the supersaturated solid solution of the α-Al matrix in the as-manufactured specimen deformed at ambient temperatures. The dynamically precipitated Si phase interacted with the introduced dislocations, enhancing the flow stress during the early stages of plastic deformation. The dynamic precipitation could contribute to the negative strain-rate sensitivity of the flow stress at an early stage of tensile deformation (including the yield strength).

DOI： 10.1016/j.scriptamat.2022.114635

Scopus

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： doi.org/10.2320/materia.61.195

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Materials Science and Engineering: A  

This study investigated the high-temperature strength of a hypereutectic Al–Fe binary alloy (Al–15%Fe) additive-manufactured by laser powder bed fusion (L-PBF). The L-PBF Al–15%Fe alloy exhibited superior yield strength to the other existing L-PBF processed alloys due to α-Al/Al6Fe eutectic structure with a nanoscale cellular morphology. The present results demonstrated the feasibility of using L-PBF processed Al–Fe alloys as high-temperature lightweight materials.

DOI： 10.1016/j.msea.2022.142782

Web of Science

Scopus

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Iron and Steel Institute of Japan  

DOI： doi.org/10.2355/isijinternational.ISIJINT-2021-506

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Materials Science and Technology  

The present study addressed the change in the microstructure of Al–2.5 wt% Fe binary alloy produced using laser powder bed fusion (L-PBF) technique by thermal exposure at 300 °C, and the associated mechanical and thermal properties were systematically examined as well. Multi-semi-cylindrical patterns corresponding to melt pools in the microstructure were macroscopically observed for the as-manufactured sample. No change in the melt-pool morphology was observed after thermal exposure for 1000 h. Inside the melt pools, a large number of the nanoscale metastable Al6Fe phase particles were uniformly distributed inside columnar grains of the α-Al matrix containing concentrated solute Fe in supersaturation. The sequential formation and coarsening of stable θ-Al13Fe4 phases were observed upon exposure to a 300 °C environment, but a considerable amount of nano-sized metastable Al6Fe phases remained even after 1000 h. Furthermore, the thermal exposure continuously reduced the concentration of solute Fe atoms in the α-Al matrix. No significant grain growth was found in α-Al matrix after 1000 h owing to the pinning effect of the dispersed fine particles on grain boundary migration. These results demonstrate a sluggish change in microstructural morphologies of the Al–2.5 wt% Fe alloy. The quantified microstructural parameters addressed dominant strengthening contributions by the solid solution of Fe element and Orowan strengthening mechanism by fine Al–Fe intermetallics in the L-PBF-produced alloy. The high strength level was sustained even after being exposed to 300 °C for long periods. The superior balance of mechanical properties and thermal conductivity can be achieved in the experimental alloys by taking advantage of the various microstructural parameters related to the Al–Fe intermetallic phases and α-Al matrix.

DOI： 10.1016/j.jmst.2021.04.038

Scopus

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Keikinzoku/Journal of Japan Institute of Light Metals  

This study was set to examine the fundamentals of solidification microstructure and room-temperature fracture toughness of different eutectic aluminum (Al) alloys strengthened by T-Al6Mg11Zn11 and/or β-Al3Mg2 intermetallic phases. The thermodynamic calculations for an Al-Mg-Zn ternary system assessed three alloy compositions of Al-22.5Mg-23.5Zn, Al-35.5Mg-2Zn and Al-34.5Mg-5Zn (mol%) corresponding to α-Al/T, α-Al/β and α-Al/T/β eutectic compositions, respectively. The designed alloys were prepared by different cast process for changing the cooling rate in solidification. The Al-22.5Mg-23.5Zn and Al-35.5Mg-2Zn alloys exhibited a number of fibrous α phase surrounded by of T-phase and β-phase matrix, respectively. The morphologies of eutectic microstructures were refined by high cooling rate in solidification. The three-phase microstructure of α, T and β phases was often observed in slowly solidified Al-34.5Mg-5Zn alloy, whereas only the α/β two-phase eutectic microstructure was observed in the rapidly solidified alloy sample. The indentation fracture method using Vickers indentation test was applied to measure the room-temperature fracture toughness of the experimental alloys prepared by mold-casting. The α/β two-phase eutectic alloys exhibited a low fracture toughness of 1.1 MPa·m0.5 in comparison with the α/T two-phase eutectic alloy. The lower fracture toughness would be responsible for the brittleness of β-phase matrix in the α/β two-phase eutectic alloys.

DOI： 10.2464/jilm.72.79

Scopus

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.4164/sptj.59.511

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ISIJ International  

The influence of different stabilizing elements (Nb, Ti and Zr) which are added to stabilize interstitial elements in the ferrite matrix on the ductile-brittle transition temperature (DBTT) of 18Cr ferritic stainless steels was systematically investigated at different temperatures ranging from −25°C to 75°C. Hot-rolled sheets of 18 mass% Cr ferritic stainless steels containing a trace amount (0.1 atomic%) of Nb, Ti or Zr were studied. The added stabilizing elements formed precipitates of carbides/nitrides in all the steels tested in the present study. The particle diameter of the precipitates observed in the Nb-added steel was much smaller than those in the other steels. The measured DBTTs of the Base steel and the Nb-added, Ti-added and Zr-added steels were 39°C, −3°C, 39°C and 11°C, respectively. Although initiation of cleavage cracks in each steel occurred independent of the kind of stabilizing element, the Nb-added steel exhibited a relatively higher Charpy impact value due to ductile plastic deformation following cleavage crack initiation, resulting in a lower DBTT (superior impact toughness). The occurrence of plastic deformation in the Nb-added steel is considered to be due to the fine carbide and/or nitride precipitates which were homogenously distributed in the material. Detailed analyses of the fracture surfaces were also performed for the other steels, and the results were used as a basis for discussing the effects of each stabilizing element on the DBTT of 18Cr ferritic stainless steels in terms of the precipitation morphologies observed in the ferrite matrix.

DOI： 10.2355/isijinternational.ISIJINT-2021-506

Scopus

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2464/JILM.72.381

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Materials Transactions  

In the present study, we investigated the effects of Cu or Ni additions on the precipitation of intermetallic phases in the heat-resistant aluminum alloy with a ternary composition of Al5Mg3.5Zn (mol%). The quaternary alloys with 1 mol%Cu or 1 mol%Ni content were solution-treated at 480°C and subsequently aged at 300°C for different periods. Both Cu and Ni additions have a slight effect on the agehardening of these alloys at 300°C. The added Cu element partitioned into not only the T-Al6Mg11Zn11 phase but

DOI： 10.2320/matertrans.MT-L2021021

Scopus

Other Link： https://www.jstage.jst.go.jp/article/matertrans/63/4/63_MT-L2021021/_article/-char/ja/

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s10853-022-07119-6

Scopus

Other Link： https://link.springer.com/article/10.1007/s10853-022-07119-6

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy  

In the laser beam powder bed fusion (PBF-LB) processes, laser parameters need to be customized for fabricating dense components. Al-Si alloys are representative Al alloys used for the PBF-LB processes. The Al-Si alloys fabricated by the PBF-LB processes exhibit characteristic microstructures and mechanical properties, which are affected by the laser parameters. This paper describes the effect of laser conditions on the relative density, microstructure, and mechanical properties of Al-12Si (mass%) alloy fabricated by the PBF-LB process. The first topic is a machine-learning-assisted exploration of laser parameters (laser power and scan speed) for fabricating dense Al-12Si alloy parts. Using a neural network model, the laser condition range for fabricating dense Al-12Si alloy parts is predicted. A methodology for accurately predicting the laser condition range for fabricating dense components is introduced. The second topic is controlling the microstructures and mechanical properties of the dense Al-12Si alloys. Variations in α-Al crystal grain size/orientation, the width of primary α-Al phase, and solute Si content in α-Al matrix with laser conditions are introduced. The changes in mechanical properties with laser conditions and correlation with microstructural features are also described.

DOI： 10.2497/jjspm.69.417

Scopus

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Keikinzoku/Journal of Japan Institute of Light Metals  

The effect of Cu or Ni addition on creep properties of a heat-resistant aluminum (Al) alloy (with a composition of Al-5Mg-3.5Zn (mol%)) strengthened by precipitates of T-Al6Mg11Zn11 intermetallic phase was investigated. The quaternary alloys with various Cu contents (0.25-3 mol%) or Ni contents (0.5-2 mol%) were solution-treated at 470 °C and then aged at 200°C for 10 hours. The creep tests were conducted using the heat-treated specimens at 200°C under 105 MPa. Both Cu and Ni additions increased the creep rupture time. The 1 mol% Cu added alloy exhibited the longest creep rupture time due to the enhanced precipitation of the refined intragranular phases (T or MgZn2 phases). However, more than 2 mol% Cu addition led to the transition of T phase to S-Al2CuMg phase formed on grain boundaries. The phase transition might have a detrimental effect on creep rupture time. In the Ni-added alloy specimen, the creep rupture time became longest when 1 mol% Ni was added. The added Ni element promoted the formation of the Al3Ni phase on the grain boundaries, resulting in the suppression of connecting cavities formed on grain boundaries in creep deformation.

DOI： 10.2464/JILM.72.473

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.addlet.2021.100008

Scopus

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Intermetallics  

This study was undertaken to understand the fundamentals of T-Al6Mg11Zn11 intermetallic phase precipitation in heat-resistant Al–Mg–Zn ternary alloys, with the goal of further strength improvements. The thermodynamic assessment involved three alloy compositions, Al–4Mg–4.5Zn, Al–5Mg–3.5Zn, and Al–7Mg–1.5Zn (at%), with the T phase in a fixed fraction (approximately 6–7.5%) in equilibrium with the α-Al phase at 300 °C. The alloy compositions were set on different tie-lines between the α-Al and T phases in the two-phase region, resulting in varied compositions of each phase. In the three experimental alloys aged at 300 °C, the T phase precipitated on the grain boundaries of the α-Al matrix, and granular precipitates were homogeneously dispersed intragranularly. There was no significant difference in the precipitation morphology. It was demonstrated that the lattice parameters of the T and α-Al phases could be controlled based on the alloy composition and applied heat treatments. However, the lattice parameters have no significant effect on the precipitation morphologies of the thermodynamically stable T phase in the Al–Mg–Zn ternary alloys. The Zn-rich Al–4Mg–4.5Zn alloy exhibited a pronounced softening behavior after 10 h of aging due to the enhanced coarsening of precipitates in the α-Al matrix. The thermal instability of the precipitates was responsible for the transformation sequence from the initially formed metastable phases (η-Zn2Mg associated phases) to the stable T phase. These results provided a fundamental insight that alloy strengthening by introducing thermodynamically stable intermetallic phases is essential for sustaining the strength of heat-resistant Al–Mg–Zn ternary alloys after long-term treatment at elevated temperatures.

DOI： 10.1016/j.intermet.2021.107364

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Additive Manufacturing  

To elucidate the possibility of controlling the microstructure and mechanical properties of Al–Si alloys additive-manufactured by laser powder bed fusion (L–PBF), the relationship among the laser conditions, microstructural characteristics (crystal grain, cellular microstructure, and solute Si in α-Al matrix), and tensile properties of L–PBF manufactured AlSi12 alloy samples was investigated. The crystal grain size and fraction of <001> oriented α-Al crystal grains toward the building direction increased as the laser power became higher and scanning velocity became slower. The width of cellular microstructure (sub–cell size) where the primary α-Al phase was surrounded by α-Al/Si eutectic microstructure increased as the laser power became higher and scanning velocity became slower. The refinement of microstructure was attributed to the solidification under high cooling rate, which was achieved by low laser power and high scanning velocity. The area fraction of Si phase analyzed from FE–SEM images tended to decrease as the laser power became higher and scanning velocity became slower, suggesting the possibility of solute Si concentration in α-Al matrix controlled by laser conditions. The STEM/EDS analysis revealed high concentration of solute Si in the α-Al matrix (above a solubility limit of 1.5 mol% in the Al–Si binary system) of L–PBF manufactured AlSi12 alloy samples and its concentration became higher in the sample manufactured using a higher laser power. The tensile tests of as–built AlSi12 specimens fabricated under various laser conditions were also performed. High strength and high ductility tended to be achieved when high power laser was applied in slow laser scanning velocity. The 0.2% proof stress was relatively higher when the laser scanning velocity was faster. The mechanical properties correlated with crystal grain size and sub–cell size rather than solute Si in the α-Al matrix. These results provide new insights to control mechanical performance of AlSi12 alloy via L–PBF processing parameters.

DOI： 10.1016/j.addma.2021.102383

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Materials  

The precipitation of intermetallic phases and the associated hardening by artificial aging treatments at elevated temperatures above 400◦ C were systematically investigated in the commer-cially available AC2B alloy with a nominal composition of Al–6Si–3Cu (mass%). The natural age hardening of the artificially aged samples at various temperatures was also examined. A slight increase in hardness (approximately 5 HV) of the AC2B alloy was observed at an elevated temperature of 480◦ C. The hardness change is attributed to the precipitation of metastable phases associated with the α-Al15 (Fe, Mn)3 Si2 phase containing a large amount of impurity elements (Fe and Mn). At a lower temperature of 400◦ C, a slight artificial-age hardening appeared. Subsequently, the hardness decreased moderately. This phenomenon was attributed to the precipitation of stable θ-Al2 Cu and Q-Al4 Cu2 Mg8 Si6 phases and their coarsening after a long duration. The precipitation sequence was rationalized by thermodynamic calculations for the Al–Si–Cu–Fe–Mn–Mg system. The natural age-hardening behavior significantly varied depending on the prior artificial aging temperatures ranging from 400◦ C to 500◦ C. The natural age-hardening was found to strongly depend on the solute contents of Cu and Si in the Al matrix. This study provides fundamental insights into controlling the strength level of commercial Al–Si–Cu cast alloys with impurity elements using the cooling process after solution treatment at elevated temperatures above 400◦ C.

DOI： 10.3390/ma14237155

Web of Science

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier Ltd.  

In this study, an attempt is made to control the WC-Co two-phase microstructures by laser powder-bed fusion (LPBF) process using cemented carbide powders with different compositions of WC-25Co (mass%) and WC-17Co (mass%) and post heat-treatment at 1380 °C. The as-built cemented carbide samples had different microstructures from those of the cemented carbides fabricated by conventional manufacturing methods. The microstructures of the as-fabricated WC-25Co and WC-17Co cemented carbides were characterized by two types of regions. Region 1 consisted of W2C and W3Co3C phases, including numerous pores and defects. Region 2 consisted of WC and Co phases. Post heat-treatment of the LPBF-built WC-25Co sample at 1380 °C led to the formation of a defect-free WC-Co two-phase microstructure. In contrast, the W3Co3C phase remained in the LPBF-built WC-17Co sample even after heat treatment. The addition of carbon to the WC-17Co powder prevented the formation of the W3Co3C phase in the cemented carbide processed by LPBF and subsequent heat treatments. The addition of carbon to the WC-17Co powder had a slight effect on the hardness of as-fabricated samples, but reduced the hardness of heat-treated samples. The reduced hardness was attributed to the increased volume fractions of the WC and W3Co3C phases.

DOI： 10.1016/j.matdes.2021.110034

Scopus

Other Link： https://www.sciencedirect.com/science/article/pii/S026412752100589X

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Materials Science and Engineering A  

The effects of a trace amount (~0.1 at.%) of added stabilizing elements (Nb, Ti, and Zr) on the tensile properties of 18Cr ferritic stainless steel sheets at strain rates ranging from 10−3–102 s−1 (from ordinary quasi-static deformation to dynamic deformation) were investigated. The additional Ti or Zr elements formed coarse carbide or nitride precipitates, which consumed interstitial solute elements (C and/or N) in the ferrite matrix. In the Nb-added steel, however, only fine NbN precipitates with a few hundred nanometers in size were observed locally, implying a small amount of solute Nb in the ferrite matrix. Ti or Zr additions had only a slight effect on the deformation resistance of 18Cr ferritic steel sheets and strain rate sensitivity (m) of the flow stress, however, the Nb addition increased the deformation resistance and significantly reduced the strain rate sensitivity. The measured activation volume (v*) values of the Ti- and Zr-added steels (62 b3 and 66 b3) were almost equivalent to one of the 18Cr base steel (64 b3). This result suggested that a general thermally activated process for screw dislocation motion is controlled by double-kink nucleation, which is slightly affected by Ti or Zr additions. The high v* value (106 b3) of the Nb-added steel indicated that the thermally activated process of plastic deformation would be associated with the substitutional solute Nb atoms (act as short-range obstacles) interacting with the moving dislocations. These results showed that the Nb element played a distinct role in plastic deformation from the other stabilizing elements of Ti and Zr.

DOI： 10.1016/j.msea.2021.141866

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Scripta Materialia  

Imitating crystal structures offers new avenues to design lattice structures composed of unit cells with nodes (act as atoms) and struts (act as atomic bonds). We found out unique dual plateau regions in the stress–strain curves of lattice structures inspired by topologically close-packed (TCP) structure of C15 Laves phase (AB2-type intermetallic compounds) and manufactured via the laser powder bed fusion. X-ray computed tomography of compressively deformed lattice structures as well as finite element analysis revealed that the existence of two kinds of units with different relative density caused the dual plateau regions. In addition, the C15 lattice structures exhibited a hybrid deformation mode of bending- and stretch-dominated deformations and can absorb high total energy of 5.0 MJ·m−3 in two stress levels.

DOI： 10.1016/j.scriptamat.2021.114003

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier B.V.  

DOI： 10.1016/j.jajp.2021.100068

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier B.V  

DOI： 10.1016/j.msea.2021.141459

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3390/cryst11030320

Language：English   Publishing type：Research paper (scientific journal)   Publisher：John Wiley & Sons, Inc.  

DOI： 10.1002/adem.202001284

DOI： 10.1002/adem.202170017

Other Link： https://onlinelibrary.wiley.com/doi/10.1002/adem.202170017

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier B.V.  

DOI： 10.1016/j.msea.2020.140591

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier Ltd.  

DOI： 10.1016/j.matdes.2020.109416

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier B.V.  

DOI： 10.1016/j.jmatprotec.2020.116843

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier B.V.  

DOI： 10.1016/j.msea.2021.140861

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier B.V.  

DOI： 10.1016/j.msea.2020.140455

Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Trans Tech Publications Ltd  

DOI： 10.4028/www.scientific.net/MSF.1016.1175

Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Trans Tech Publications Ltd  

DOI： 10.4028/www.scientific.net/MSF.1016.826

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jmbbm.2020.104130

Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2464/jilm.71.275

Scopus

Other Link： https://www.jstage.jst.go.jp/article/jilm/71/7/71_710701/_article/-char/ja/

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3390/cryst10111007

Other Link： https://www.mdpi.com/2073-4352/10/11/1007

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.intermet.2020.106892

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.addma.2020.101308

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.intermet.2020.106881

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3390/ma13183927

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.addma.2020.101436

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3390/ma13132902

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Other Link： https://www.mdpi.com/1996-1944/13/13/2902

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2497/jjspm.67.313

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3390/ma13112487

Web of Science

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2355/isijinternational.ISIJINT-2019-448

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Other Link： https://www.jstage.jst.go.jp/article/isijinternational/60/4/60_ISIJINT-2019-448/_article/-char/ja

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.11283/jlwa.58.102s

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3390/ma13051238

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Other Link： https://www.mdpi.com/1996-1944/13/5/1238

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.addma.2020.101152

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2320/matertrans.MT-M2019237

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jmatprotec.2019.116388

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.msea.2020.139000

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jmst.2019.06.015

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.msea.2019.138710

Authorship：Lead author   Language：Japanese  

DOI： https://doi.org/10.2497/jjspm.66.573

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.msea.2019.138330

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Authorship：Lead author   Language：Japanese  

DOI： 10.11279/jfes.91.612

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.msea.2019.138247

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1002/adem.201900571

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2355/tetsutohagane.105.675

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.apt.2019.06.024

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2355/tetsutohagane.TETSU-2018-147

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2355/tetsutohagane.TETSU-2018-146

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.intermet.2019.03.011

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.addma.2019.04.018

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.14957/fgms.33.38

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jmatprotec.2019.02.012

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2464/jilm.69.93

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan  

DOI： 10.2355/tetsutohagane.TETSU-2018-064

Scopus

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.msea.2018.10.034

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jallcom.2018.08.211

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jmatprotec.2018.09.010

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1557/adv.2019.153

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1557/adv.2019.107

Web of Science

Publisher：Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan  

DOI： 10.2355/tetsutohagane.TETSU-2018-150

Scopus

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy  

DOI： 10.2497/jjspm.66.573

Scopus

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.matdes.2018.08.005

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3390/met8060440

Web of Science

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jmatprotec.2018.06.010

Scopus

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2464/jilm.68.250

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

We designed two types of Al-based alloy composites reinforced by η-Zn2Mg (hexagonal) and T-Al6Mg11Zn11 (cubic) intermetallic phases using monovariant eutectic reactions in the Al–Mg–Zn ternary system and then attempted to fabricate them using solidification. Thermodynamic assessment revealed two alloy compositions of Al–18Mg–36Zn and Al–22.5Mg–23.5Zn (at%) with the α-Al (fcc) phase reinforced with high fractions (>50%) of the η and T phases. Both alloys exhibited fine two-phase eutectic microstructures consisting of α/η and α/T phases, respectively. The morphology of the α-Al phase in the eutectic colonies varied from lamellae to fibers upon changing the neighboring intermetallic phase. These eutectic microstructures exhibit high stability at an elevated temperature of 300 °C. In addition, the size and spacing of the α-Al phase could be controlled by changing the cooling rate during solidification. The fabricated composites exhibited high hardness values exceeding 220 HV, which were much superior to those of conventional Al alloys. The calculated solidification path and component partitioning in the liquid phase during solidification provided insights into the solidification segregation of Zn element in the Al–18Mg–36Zn alloy. The Zn-enriched regions would enhance the local microstructural change at elevated temperatures, which confirmed by the microstructural observations of the alloy exposed at 300 °C

DOI： 10.1016/j.intermet.2018.01.018

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jmatprotec.2017.10.054

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.matchar.2017.11.052

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2355/isijinternational.ISIJINT-2018-036

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2464/jilm.67.582

Authorship：Lead author   Language：Japanese  

DOI： 10.2464/jilm.67.571

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.msea.2017.08.029

Web of Science

Language：Japanese   Publishing type：Research paper (scientific journal)  

Porous metals show some unique properties, which bulk metals cannot exhibit. Especially, iron-based porous metals are expected to be applied to structural components because of their high strength, high rigidity, low material cost and so on. In this research, we synthesized porous Fe/TiB2 composites by Fe-Ti-B combustion reaction. Iron, titanium and boron powders were blended to synthesize 30 to 60vol%TiB2 particles in Fe matrix after the combustion synthesis reaction. Four kinds of iron powders (powder size: < 53 μm, < 150 μm, 600 μm and 850-1000 μm) were used. The blended powder was heated to induce the combustion synthesis reaction. When < 53 μm and < 150 μm iron powders were used, irregular shaped and open pores were formed. On the other hand, when 600 μm and 850-1000 μm iron powders were used, spherical pores whose sizes and shapes were similar to those of iron powders were formed

DOI： http://doi.org/10.2497/jjspm.64.288

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.msea.2017.05.015

Web of Science

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy  

DOI： 10.2497/jjspm.64.288

Scopus

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

In the present study, we have attempted to produce the porous Ti–Al intermetallic based alloys by pressure-sintering of the elemental powders of Ti and Al through a combustion reaction, with a NaCl space holder to achieve the development of a highly porous structure. The powders of Ti (particle size: <45 μm) and Al (particle size: <45 μm) were mixed to various total compositions of Ti–0-40 Al (at.%), and NaCl (particle size: 300-400 μm) was mixed with the Ti/Al powder to give a highly porous structure. The mixed powder was sintered at 700 oC under a constant pressure of 30 MPa to form cylindrical specimens with a diameter of 20 mm. The soaking of the specimens in pure water allows for the removal of NaCl (with a volume fraction of 60 %) and the formation of the pores to achieve a controlled relative density of 0.4. The present process can produce porous Ti–Al alloys with various compositions. In as-sintered Ti–Al specimens, an inhomogeneous microstructure consisting of Ti particles surrounded by the a Ti–Al alloy layer (various Ti–Al intermetallic phases) was observed. The as-sintered specimens exhibited the brittle behavior under compression, which is independent of their Al content. However, in a Ti–20Al alloy heat-treated at 1300 °C, a nearly Ti3Al single-phase microstructure appeared in the porous specimen. The heat-treated porous Ti–20Al alloy shows both a high plateau-strength level of approximately 100 MPa and a high plateau-end strain over 50%, resulting in a high absorption energy. The present results demonstrate that controlling the microstructure for the formation of the Ti3Al single-phase would be an effective method to achieve high energy absorption capacity of the porous Ti–Al alloy.

DOI： 10.1557/adv.2017.123

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

The three-phase, (Mo,Nb)ss/(Mo,Nb)5Si3/(Mo,Nb)5SiB2, Bcc/T1/T2 microstructures that develop in Mo–Nb–Si–B alloys have been examined in arc cast and directionally solidified samples to identify the phase sequencing during solidification. A Mo-32.6Nb-19.5Si-4.7B (at.%) alloy was directionally solidified using an optical floating zone (OFZ) furnace in a flowing Ar gas atmosphere at a constant growth rate of 10 mm/h. The microstructure of the directionally solidified alloy is characterized by an elongated T2 phase surrounded by bcc and T1 phases with an interwoven morphology From the evaluation of the microstructures in arc cast ingots of several alloys at a constant 32.6 at%Nb composition, the path of the liquidus valleys with decreasing temperature has been determined to intersect at a common point that establishes the solidification reaction as a eutectic. The incorporation of the experimental results into a computational thermodynamic analysis provides insight on the partitioning of components within each phase during solidification

DOI： doi:10.1016/j.intermet.2016.01.001

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： http://dx.doi.org/10.1016/j.msea.2016.03.038

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.intermet.2015.11.003

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2355/isijinternational.ISIJINT-2015-441

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2355/tetsutohagane.TETSU-2015-063

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.intermet.2015.07.011

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2355/isijinternational.55.1454

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： DOI: 10.1557/opl.201 .

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.intermet.2014.06.003

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Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

We have examined the growth kinetics of Fe-Zn intermetallics layers formed on Fe-1.5Mn (α-Fe single phase) and Fe-3.5Mn-0.1C (γ-Fe+α-Fe two phase) steel sheets dipped in pure Zn melt at 460 ºC. In an early stage of dipping, FeZn13-ζ phase layer is initially formed and its thickness slightly increases with increasing dipping time till about 10 s, and then all Fe-Zn intermetallics layers (ζ, δ1, Γ) grow following a parabolic law. The growth kinetics can be recognized in both steels. This result demonstrates a slight effect of steel microstructure on the formation of Fe-Zn intermetallics layers. The composition analysis revealed a significant Fe dissolution into pure Zn melt in an early stage of dipping. The supersaturated Fe in Zn melt would provide the driving force for the crystallization of ζ phase layer on steel sheets. The continuous layer of ζ phase would control Fe diffusion for the following growth of the other Fe-Zn intermetallics layers.

Language：Japanese   Publishing type：Research paper (scientific journal)  

Creep of carbon free Fe-20Cr-30Ni-2Nb (at.%) steels strengthened by Fe2Nb Laves phase on grain boundaries has been examined in air and steam atmospheres at 1073 K/70 MPa. Sufficiently covering grain boundaries by stable Laves phase can reduce the creep rate, resulting in a significant extension of the creep rupture life without a loss of creep ductility in steam atmosphere as well as air. This effect becomes remarkable in higher area fractions of Laves phase on grain boundaries (ρ) than 80%. The creep rupture strain slightly decrease by steam atmosphere, which would be associated with the interglanular oxidation and its related cracks propagation along grain boundaries enhanced by steam atmosphere in the creep acceleration stage. Its effect can be suppressed by covering grain boundaries by Laves phase (increasing ρ). Therefore, Grain Boundary Precipitation Strengthening by stable Laves phase is a key mechanism for use of materials for boiler tubes in the innovative advanced ultra-super critical (A-USC) thermal power plants to be operated above 973 K.

Authorship：Lead author   Language：English  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.scriptamat.2012.12.019

Web of Science

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： DOI: 10.1557/opl.2012.

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.scriptamat.2011.01.026

Web of Science

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1088/1742-6596/240/1/012015

Web of Science

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.matlet.2009.05.021

Web of Science

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.scriptamat.2008.12.018

Web of Science

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.scriptamat.2008.09.002

Web of Science

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2320/matertrans.MD200809

Web of Science

Language：English   Publishing type：Research paper (scientific journal)  

Web of Science

Publishing type：Research paper (bulletin of university, research institution)  

Publishing type：Research paper (bulletin of university, research institution)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s10853-008-2971-9

Web of Science

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s10853-008-2972-8

Web of Science

Language：Japanese  

Language：Japanese   Publishing type：Research paper (scientific journal)  

The formation behavior of polycrystalline silicon thin films during the aluminum induced crystallization (AIC) was investigated by in-situ heating transmission electron microscopy (TEM). The electron dispersive X-ray spectroscopy (EDS) analysis of annealed sample was showed that layer exchange of the a-Si/Al film is occurred during the annealing. Furthermore, from the in-situ heating TEM observation and EDS analysis of as-deposited sample, it was confirmed the co-existence of Si and Al in a-Si/Al film. The mechanism of AIC and layer exchange were discussed from the experimental results and the phase diagram of Al-Si system.

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2320/matertrans.MRA20073121

Web of Science

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2320/matertrans.ME200715

Web of Science

Language：English   Publishing type：Research paper (scientific journal)  

Web of Science

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：English   Publishing type：Research paper (scientific journal)  

Web of Science

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

DOI： 10.2355/isijinternational.48.1114

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1166/jnn.2007.073

Web of Science

Language：Japanese  

Language：English   Publishing type：Research paper (scientific journal)  

Web of Science

Language：Japanese  

Language：Japanese  

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Web of Science

Language：English   Publishing type：Research paper (scientific journal)  

Web of Science

Language：English   Publishing type：Research paper (scientific journal)  

Web of Science

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Language：Japanese  

Language：Japanese  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Polycrystalline silicon (poly-Si) thin films with various amorphous Si (a-Si)/Aluminum (Al) thickness ratio have been prepared by Al-induced crystallization (AIC). In order to investigate the formation process of poly-Si thin film produced by AIC, the crystal orientation analysis by SEM/EBSP method and in-situ TEM observation were carried out. It was found that the a-Si/Al thickness ratio of about 1:1 is suitable to achieve a flat surface of poly-Si. Furthermore, in-situ TEM observation shows that Si is crystallized through the non-equilibrium a-Si/Al solid solution.

Language：English   Publishing type：Research paper (scientific journal)  

Web of Science

Language：Japanese   Publishing type：Research paper (scientific journal)  

  In this study, the energy and atomic structure of the <110> symmetric tilt boundaries in palladium were calculated using a molecular dynamics (MD) method and the electronic structures of hydrogen in the bulk and at the grain boundaries were calculated using discrete-variational Xα (DV-Xα) molecular orbital cluster calculaion by solving Hartree-Fock-Slater equation.    The result of MD simulation revealed that the energy of the <110> symmetric tilt boundary of palladium depended on the misorientation angle and that there were large energy cusps at the misorientation angles which correspond to the {111}Σ3 and {113}Σ11 symmetric tilt boundaries. The atomic structure of all <110> symmetric tilt boundaries could consist of the combination of the {331} Σ19, {111}Σ3 and {113}Σ11 structural units and {110}Σ1 and {001}Σ1 single crystal units.    The result of DV-Xα molecular orbital cluster calculation showed that the interstitial hydrogen atoms induced the palladium-hydrogen chemical bond which had a different energy level from the palladium-palladium bond. The component of the palladium-hydrogen bond at the grain boundaries was similar to those in the bulk palladium. It is clarified that electronic structure near the grain boundary is different from that in the perfect crystal.

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1143/JJAP.44.4770

Web of Science

Language：Japanese  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

DOI： 10.2320/matertrans.45.2099

Language：English   Publishing type：Research paper (scientific journal)  

Web of Science

Publishing type：Research paper (scientific journal)  

DOI： 10.2320/jinstmet.68.240

Publishing type：Research paper (scientific journal)  

DOI： 10.2320/matertrans.45.1687

Publishing type：Research paper (scientific journal)  

Language：Japanese  

Language：Japanese  

Language：English   Publishing type：Research paper (scientific journal)  

Web of Science

Language：Japanese  

Language：Japanese Book type：Scholarly book

Total pages：12   Language：Japanese Book type：Textbook, survey, introduction

Total pages：4   Language：Japanese Book type：Report

Language：Japanese

Language：Japanese

Event date： 2024.12

Language：English   Presentation type：Poster presentation  

Venue：Boston   Country：United States  

Event date： 2024.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：新潟コンベンションセンター   Country：Japan  

Event date： 2024.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：新潟コンベンションセンター   Country：Japan  

Event date： 2024.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：新潟コンベンションセンター   Country：Japan  

Event date： 2024.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：新潟コンベンションセンター   Country：Japan  

Event date： 2024.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：新潟コンベンションセンター   Country：Japan  

Event date： 2024.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：新潟コンベンションセンター   Country：Japan  

Event date： 2024.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：新潟コンベンションセンター   Country：Japan  

Event date： 2024.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：新潟コンベンションセンター   Country：Japan  

Event date： 2024.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：新潟コンベンションセンター   Country：Japan  

Event date： 2024.11

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Venue：東北大学   Country：Japan  

Event date： 2024.11

Language：Japanese   Presentation type：Poster presentation  

Venue：群馬大学   Country：Japan  

Event date： 2024.11

Language：Japanese   Presentation type：Poster presentation  

Venue：群馬大学   Country：Japan  

Event date： 2024.10

Language：English   Presentation type：Oral presentation (general)  

Venue：Yokohama   Country：Japan  

Event date： 2024.10

Language：English   Presentation type：Oral presentation (general)  

Venue：Yokohama   Country：Japan  

Event date： 2024.10

Language：English   Presentation type：Poster presentation  

Venue：Yokohama   Country：Japan  

Event date： 2024.10

Language：English   Presentation type：Oral presentation (general)  

Venue：Yokohama   Country：Japan  

Event date： 2024.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学   Country：Japan  

Event date： 2024.9

Language：Japanese   Presentation type：Poster presentation  

Venue：大阪大学   Country：Japan  

Event date： 2024.9

Language：Japanese   Presentation type：Poster presentation  

Venue：大阪大学   Country：Japan  

Event date： 2024.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学   Country：Japan  

Event date： 2024.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学   Country：Japan  

Event date： 2024.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学   Country：Japan  

Event date： 2024.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学   Country：Japan  

Event date： 2024.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学   Country：Japan  

Event date： 2024.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学   Country：Japan  

Event date： 2024.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学   Country：Japan  

Event date： 2024.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大分県日田市   Country：Japan  

Event date： 2024.9

Language：English   Presentation type：Oral presentation (general)  

Venue：DTU Risø Campus, Roskilde   Country：Denmark  

Event date： 2024.9

Language：English   Presentation type：Oral presentation (general)  

Venue：DTU Risø Campus, Roskilde   Country：Denmark  

Event date： 2024.9

Language：English   Presentation type：Oral presentation (general)  

Venue：DTU Risø Campus, Roskilde   Country：Denmark  

Event date： 2024.7

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Venue：東京大学   Country：Japan  

Event date： 2024.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Atlanta   Country：United States  

Event date： 2024.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Atlanta   Country：United States  

Event date： 2024.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Atlanta   Country：United States  

Event date： 2024.6

Language：English   Presentation type：Oral presentation (invited, special)  

Venue：Jeju   Country：Korea, Republic of  

Event date： 2024.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Jeju   Country：Korea, Republic of  

Event date： 2024.5

Language：Japanese   Presentation type：Poster presentation  

Venue：名古屋大学　東山キャンパス   Country：Japan  

Event date： 2024.5

Language：Japanese   Presentation type：Poster presentation  

Venue：名古屋大学　東山キャンパス   Country：Japan  

Event date： 2024.5

Language：Japanese   Presentation type：Poster presentation  

Venue：名古屋大学　東山キャンパス   Country：Japan  

Event date： 2024.5

Language：Japanese   Presentation type：Poster presentation  

Venue：名古屋大学　東山キャンパス   Country：Japan  

Event date： 2024.5

Language：Japanese   Presentation type：Poster presentation  

Venue：名古屋大学　東山キャンパス   Country：Japan  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京理科大学　葛飾キャンパス   Country：Japan  

Event date： 2024.3

Language：Japanese   Presentation type：Poster presentation  

Venue：東京理科大学　葛飾キャンパス   Country：Japan  

Event date： 2024.3

Language：Japanese   Presentation type：Poster presentation  

Venue：東京理科大学　葛飾キャンパス   Country：Japan  

Event date： 2024.3

Language：Japanese   Presentation type：Poster presentation  

Venue：東京理科大学　葛飾キャンパス   Country：Japan  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京理科大学　葛飾キャンパス   Country：Japan  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京理科大学　葛飾キャンパス   Country：Japan  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京理科大学　葛飾キャンパス   Country：Japan  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京理科大学　葛飾キャンパス   Country：Japan  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京理科大学　葛飾キャンパス   Country：Japan  

Event date： 2023.11 - 2023.12

Language：English   Presentation type：Oral presentation (general)  

Venue：Boston   Country：United States  

Event date： 2023.11

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Venue：Jeju   Country：Korea, Republic of  

Event date： 2023.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Jeju   Country：Korea, Republic of  

Event date： 2023.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Jeju   Country：Korea, Republic of  

Event date： 2023.11

Language：Japanese   Presentation type：Poster presentation  

Venue：東京都立大学　南大沢キャンパス   Country：Japan  

Event date： 2023.11

Language：Japanese   Presentation type：Poster presentation  

Venue：東京都立大学　南大沢キャンパス   Country：Japan  

Event date： 2023.11

Language：Japanese   Presentation type：Poster presentation  

Venue：東京都立大学　南大沢キャンパス   Country：Japan  

Event date： 2023.10

Language：English   Presentation type：Oral presentation (invited, special)  

Venue：Seoul   Country：Korea, Republic of  

Other Link： http://www.galvatech2023.org/technicalprogram/GALVATECH2023_Presentation_Schedule_v2_20230726.pdf

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山大学   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山大学   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山大学   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山大学   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山大学   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山大学   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山大学   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山大学   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Venue：富山大学   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山大学   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山大学   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山大学   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山大学   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山大学   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山大学   Country：Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2023.7

Language：English   Presentation type：Oral presentation (invited, special)  

Venue：Vienna   Country：Austria  

Event date： 2023.7

Language：English   Presentation type：Oral presentation (invited, special)  

Venue：Vienna   Country：Austria  

Event date： 2023.7

Language：English   Presentation type：Poster presentation  

Venue：Vienna   Country：Austria  

Event date： 2023.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Vienna   Country：Austria  

Event date： 2023.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Vienna   Country：Austria  

Event date： 2023.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Vienna   Country：Austria  

Event date： 2023.7

Language：English   Presentation type：Poster presentation  

Venue：Vienna   Country：Austria  

Event date： 2023.7

Language：English   Presentation type：Poster presentation  

Venue：Vienna   Country：Austria  

Event date： 2023.7

Language：English   Presentation type：Poster presentation  

Venue：Vienna   Country：Austria  

Event date： 2023.7

Language：English   Presentation type：Poster presentation  

Venue：Vienna   Country：Austria  

Event date： 2023.7

Language：English   Presentation type：Poster presentation  

Venue：Vienna   Country：Austria  

Event date： 2023.5

Language：Japanese   Presentation type：Poster presentation  

Venue：香川大学幸町キャンパス   Country：Japan  

Event date： 2023.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：香川大学幸町キャンパス   Country：Japan  

Event date： 2023.5

Language：Japanese   Presentation type：Poster presentation  

Venue：香川大学幸町キャンパス   Country：Japan  

Event date： 2023.5

Language：Japanese   Presentation type：Poster presentation  

Venue：香川大学幸町キャンパス   Country：Japan  

Event date： 2023.5

Language：Japanese   Presentation type：Poster presentation  

Venue：香川大学幸町キャンパス   Country：Japan  

Event date： 2023.5

Language：Japanese   Presentation type：Poster presentation  

Venue：香川大学幸町キャンパス   Country：Japan  

Event date： 2023.5

Language：Japanese   Presentation type：Poster presentation  

Venue：香川大学幸町キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (keynote)  

Venue：東京大学   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Poster presentation  

Venue：東京大学   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Poster presentation