Faculty Profiles - KOBASHI, Makoto

Papers - KOBASHI, Makoto

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Solid Fe/Liquid Zn Interfacial Reaction of Hot-Dip Galvanized Fe-Si Alloy Sheets Invited Reviewed

Naoki Takata, Kunihisa Hayano, Asuka Suzuki, Makoto Kobashi

Proceedings of GALVATEC2017 (11th International Conference on Zinc and Zinc Alloy Coated Steel Sheet) page： 177-181 2017.11

金属粉末レーザ積層造形法によって作製されたAL-10Si-0.4Mg合金の組織と機械的性質 Invited Reviewed

高田尚記, 小平寛久, 関沢圭人, 鈴木飛鳥, 小橋眞

軽金属 Vol. 67 ( 11 ) page： 582-588 2017.11

化学反応を利用したアルミニウム基複合材料の製造方法 Invited Reviewed

小橋眞, 高田尚記, 鈴木飛鳥

軽金属 Vol. 67 ( 11 ) page： 571-575 2017.11

High-stiffness and strength porous maraging steel via topology optimization and selective laser melting

A. Takezawa, Y. Koizumi, M. Kobashi

Additive Manufacturing Vol. 18 page： 194-202 2017.10

Induction-Activated Self-propagating, High-temperature Synthesis of Nickel Aluminide

M. Shekari, M. Adeli, A. Khobzi, M. Kobashi, N. Kanetake

Advanced Powder Technology Vol. 28 page： 2974-2979 2017.9

Induction-Activated Self-propagating, High-temperature Synthesis of Nickel Aluminide

M. Shekari, M. Adeli, A. Khobzi, M. Kobashi, N. Kanetake

Advanced Powder Technology Vol. 28 page： 2974-2979 2017.9

Change in Microstructure of Selectively Laser Melted AlSi10Mg Alloy with Heat Treatments Reviewed

N.Takata, H.Kodaira, K.Sekizawa, A.Suzuki, M.Kobashi

Materials Science & Engineering A Vol. 704 page： 218-228 2017.8

Change in Microstructure of Selectively Laser Melted AlSi10Mg Alloy with Heat Treatments Reviewed

N.Takata, H.Kodaira, K.Sekizawa, A.Suzuki, M.Kobashi

Materials Science & Engineering A Vol. 704 page： 218-228 2017.8

燃焼合成反応を利用したFe/TiB2複合材料の合成とポーラス化 Invited Reviewed

伊藤峻, 髙田尚記, 小橋眞

粉体および粉末冶金 Vol. 64 ( 6 ) page： 288-294 2017.6

燃焼合成反応を利用したFe/TiB2複合材料の合成とポーラス化 Invited Reviewed

伊藤峻, 髙田尚記, 小橋眞

粉体および粉末冶金 Vol. 64 ( 6 ) page： 288-294 2017.6

Compressive properties of porous Ti-Al alloys fabricated by reaction Reviewed

N. Takata, K. Uematsu, M. Kobashi

Materials Science & Engineering A Vol. 697 page： 66-70 2017.5

Implementation of DSC analysis in reaction kinetics during heating of Ti-50 at.%Al powder mixture Reviewed

M. Adeli, S. H. Seyedein, M. R. Aboutalebi, M. Kobashi, N. Kanetake

JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY Vol. 128 ( 2 ) page： 867 - 874 2017.5

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

In this study, the reactions in Ti-50 at.%Al powder mixture upon heating at constant heating rates were studied using DSC analysis. Heating up the mixture resulted in melting of aluminum at temperatures close to its melting temperature, which was manifested as an endothermic peak in DSC curves. The melting of aluminum was the onset of an intense exothermic reaction, so-called combustion synthesis reaction which results in the formation of titanium aluminide. The shift in exothermic peak temperature in various linear heating rates was used to calculate the apparent activation energy according to Kissinger-type model-free methods. Heating rates of 10, 20, 30, 40, and 50 K min(-1) were used to estimate the activation energy based on DSC data. In order to study the effect of ball-milling on reaction behavior, the starting powder mixture was ball-milled for different times, and a comparison was made between non-ball-milled and ball-milled DSC curves. The results showed that ball-milling tends to diminish the endothermic peak of melting of aluminum and shift the exothermic reaction temperature to lower temperatures, apparently altering the mechanism from a solid-liquid to an almost solid-solid one. The activation energy of the process in the non-ball-milled state was found to be close to the activation energy of diffusion of aluminum in TiAl (220 kJ mol(-1)). However, the application of same model-free methods to the ball-milled samples showed unexpectedly increased values for activation energy. It would be appropriate to check other methods as well as for calculation of activation energy in the ball-milled systems.

DOI： 10.1007/s10973-016-5982-9

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Compressive properties of porous Ti-Al alloys fabricated by reaction Reviewed

N. Takata, K. Uematsu, M. Kobashi

Materials Science & Engineering A Vol. 697 page： 66-70 2017.5

粉末冶金法を利用したポーラス金属の製造プロセスおよび気孔構造制御 Invited Reviewed

小橋　眞

粉体および粉末冶金 Vol. 64 ( 2 ) page： 61-67 2017.3

粉末冶金法を利用したポーラス金属の製造プロセスおよび気孔構造制御 Invited Reviewed

小橋眞

粉体および粉末冶金 Vol. 64 ( 2 ) page： 61-67 2017.3

Porous metal produced by selective laser melting with effective isotropic Reviewed

A. Takezawa, M.Kobashi, Y. Koizumi, M. Kitamura

International Journal of Heat and Mass Transfer Vol. 105 page： 564-572 2017.2

Porous metal produced by selective laser melting with effective isotropic thermal conductivity close to the Hashin-Shtrikman bound Reviewed

Akihiro Takezawa, Makoto Kobashi, Yuichiro Koizumi, Mitsuru Kitamura

INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER Vol. 105 page： 564 - 572 2017.2

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

Additive manufacturing may be a novel method for fabricating porous materials. These materials can achieve effective performance because of their internal geometries. Metal-additive manufacturing is expected to utilize thermal conduction materials and devices. We have developed a porous metal with effective isotropic thermal conductivity by using metal-selective laser melting additive manufacturing. The internal pore structure was designed by topology optimization, which is the most effective structural optimization technique to maximize effective thermal conductivity. The designed structure was converted to a three-dimensional STL model, which is a native digital format of additive manufacturing, and assembled as a test piece. Effective thermal conductivity was measured by a steady-state method in which the effective thermal conductivity was calculated from a one-dimensional temperature gradient and the heat flux of the test pieces. The test pieces showed an effective thermal conductivity close to the Hashin-Shtrikman or Maxwell-Eucken bound, which is the theoretical limit of effective performance with an error less than 10%. (C) 2016 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijheatmasstransfer.2016.10.006

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Porous Ti-Al Intermetallic Based Alloys Fabricated by Pressure-Sintering Elemental Powders with a Space Holder Powder Reviewed

N.Takata, K.Uematsu, M.Kobashi

MRS advances Vol. 2 ( 26 ) page： 1387-1392 2017.1

Porous Ti-Al Intermetallic Based Alloys Fabricated by Pressure-Sintering Elemental Powders with a Space holder Powder Reviewed

Naoki Takata, Keisuke Uematsu, Makoto Kobashi

MRS ADVANCES Vol. 2 ( 26 ) page： 1387 - 1392 2017

Language：English Publishing type：Research paper (scientific journal) Publisher：CAMBRIDGE UNIV PRESS

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 pm) and Al (particle size: <45 pm) were mixed to various total compositions of Ti-0-40 Al (at.%), and NaCl (particle size: 300-400 mu m) was mixed with the Ti/Al powder to give a highly porous structure. The mixed powder was sintered at 700 degrees C: 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-AI 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 degrees 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 Ti(3)AI single-phase would he an effective method to achieve high energy absorption capacity of the porous Ti Al alloy.

DOI： 10.1557/adv.2017.123

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Reactive processing of aluminum matrix composites

Makoto Kobashi, Naoki Takata, Asuka Suzuki

Journal of Japan Institute of Light Metals Vol. 67 ( 11 ) page： 571 - 575 2017

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Papers - KOBASHI, Makoto