研究者詳細 - 小橋　眞

The laser powder bed fusion (L-PBF) process provides the cellular microstructure (primary α phase surrounded by a eutectic Si network) inside hypo-eutectic Al–Si alloys. The microstructure changes to the particle-dispersed microstructure with heat treatments at around 500 °C. The microstructural change leads to a significant reduction in the tensile strength. However, the microstructural descriptors representing the cellular and particle-dispersed microstructures have not been established, resulting in difficulty in terms of discussion regarding the structure–property relationship. In this study, an attempt was made to analyze the microstructure in L-PBF-built and subsequently heat-treated Al–12Si (mass%) alloys using the persistent homology, which can analyze the spatial distributions and connections of secondary phases. The zero-dimensional persistent homology revealed that the spacing between adjacent Si particles was independent of Si particle size in the as-built alloy, whereas fewer Si particles existed near large Si particles in the heat-treated alloy. Furthermore, the first principal component of a one-dimensional persistent homology diagram would represent the microstructural characteristics from cellular to particle-dispersed morphology. These microstructural descriptors were strongly correlated with the tensile and yield strengths. This study provides a new insight into the microstructural indices describing unique microstructures in L-PBF-built alloys.

DOI： 10.3390/ma16227228

Web of Science

PubMed

researchmap

Machine learning surrogate modeling toward the design of lattice-structured heat sinks fabricated by additive manufacturing 査読有り

Asuka Suzuki, Hideto Nakatani, Makoto Kobashi

Materials & Design 230 巻頁： 111969 2023年6月

Mechanical coupling and tuned anisotropic elasticity: Numerical and experimental material design for shear-normal and shear-shear interactions 査読有り国際共著

Molavitabrizi, D; Suzuki, A; Kobashi, M; Mousavi, SM

MATERIALS & DESIGN 230 巻頁： 111950 2023年6月

Fabrication of Al-CNT composite with high hardness and electrical conductivity by controlling Al4C3 formation 査読有り

Kim, D; Hirayama, Y; Liu, Z; Takagi, K; Kobashi, M

JOURNAL OF ALLOYS AND COMPOUNDS 942 巻頁： 169102 2023年5月

B2-structured Fe<inf>3</inf>Al alloy manufactured by laser powder bed fusion: Processing, microstructure and mechanical performance 査読有り国際共著

A. M. Vilardell, L. Pelcastre, D. Nikas, P. Krakhmalev, M. Kato, N. Takata, M. Kobashi

Intermetallics 156 巻頁： 107849 2023年5月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）

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

Web of Science

Scopus

researchmap

Ultra-high coercivity Sm-Co bulk magnets with remarkable thermal stability 査読有り

Park, K; Hirayama, Y; Wang, J; Kobashi, M

SCRIPTA MATERIALIA 218 巻 2022年9月