2022 Fiscal Year Final Research Report

Fabrication and Micro/Nano Structure Control of High Entropy Alloys by Advanced Processing

Planned Research

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Project Area	High Entropy Alloys - Science of New Class of Materials Based on Elemental Multiplicity and Heterogeneity
Project/Area Number	18H05455
Research Category	Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
Allocation Type	Single-year Grants
Review Section	Science and Engineering
Research Institution	Kyoto University
Principal Investigator	Tsuji Nobuhiro 京都大学, 工学研究科, 教授 (30263213)
Co-Investigator(Kenkyū-buntansha)	千葉晶彦東北大学, 金属材料研究所, 教授 (00197617) 飴山惠立命館大学, 理工学部, 教授 (10184243) 安田秀幸京都大学, 工学研究科, 教授 (60239762)
Project Period (FY)	2018-06-29 – 2023-03-31
Keywords	ハイエントロピー合金 / 組織制御 / 凝固 / 粉末冶金 / X線CT / 超微細粒 / 調和組織 / 3Dプリンティング
Outline of Final Research Achievements	Experimental research was conducted to control nano-/micro-structures and macro morphology of high-entropy alloys through four key processes: (i) solidification and casting, (i) thermomechanical processing and heat treatment, (iii) powder metallurgy, and (iv) 3D printing, in order to clarify the unique microstructure formation process and mechanism of high-entropy alloys. Correlations between the nano-/micro-structures and various properties were clarified, and process guidelines for fabricating alloys with desirable properties were obtained. We found several novel properties and phenomena, clarified them academically, and examined the direction of practical application of high-entropy alloys through 3D printing, which is expected to be applied to high-entropy alloys. We could conduct a number of collaborative researches within the area and undertake initiatives that can be realize only in the KAKENHI priority area project.
Free Research Field	金属材料学
Academic Significance and Societal Importance of the Research Achievements	ハイエントロピー合金は、五種類以上の元素をほぼ等モル含む合金であり、鉄合金（鉄鋼材料）やアルミニウム合金のようにある特定の元素を主体として少量の合金元素を含む従来合金とは全く異なる新しい概念の合金群である。凝固・鋳造、加工熱処理、粉末冶金、3Dプリンティングという、４種類の重要プロセスを通じてハイエントロピー合金のナノ・ミクロ組織やマクロ形態の制御を行い、ハイエントロピー合金特有の組織形成過程と機構を明らかにすることができた。これらはハイエントロピー合金という新しい材料の特性を学術的に明らかにするとともに、高性能合金としての将来の社会実装に有用な知見をもたらすことのできる成果である。