| Project/Area Number |
19K14838
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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| Review Section |
Basic Section 18010:Mechanics of materials and materials-related
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| Research Institution | Tohoku University |
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Principal Investigator |
Wei Daixiu 東北大学, 金属材料研究所, 助教 (20785810)
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| Project Period (FY) |
2019-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2020)
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| Budget Amount *help |
¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2020: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
Fiscal Year 2019: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
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| Keywords | 金属材料 / 機械特性 / 第一原理計算 / 熱力学計算 / 塑性変形 / 強度 / 延性 / High entropy alloy / Stacking fault energy / Mechanical property / Plasticity / High entropy alloys / Martensite / Deformation twinning / Mechanical properties |
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| Outline of Research at the Start |
The proposed research reveals the basic understandings of the regulation of stacking fault energy and the manipulation of mechanical behaviors of high entropy alloys, which sheds light on the development of next-generation high performance alloys and the progress of phase transformation theories.
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| Outline of Final Research Achievements |
High-entropy alloys (HEAs) have attracted much attention, with stacking fault energy (SFE) affecting their mechanical behaviors. The present study revealed the principles for regulating elastic and plastic behaviors of the quaternary CoCrFeNi and quinary CoCrFeMnNi HEAs, assisted by ab initio and thermodynamics calculations. The results showed that an increase in Co content and a decrease in Fe and Ni contents reduced the SFE, but enhanced the elastic modulus, anisotropy, and lattice friction stress. Minor addition of Mo increased the lattice distortion but decreased the SFE and elastic modulus. Then, a series of strong and ductile metastable Co-rich HEAs with superior mechanical properties were proposed. The properties are enhanced by solid-solution strengthening accompanied by a low-SFE-induced restriction of planar behavior of dislocations, mechanical twinning, and strain-induced martensitic transformation. The findings shed light on the development of high-performance HEAs.
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| Academic Significance and Societal Importance of the Research Achievements |
金属材料が工業的に用いられる材料の中でも重要な地位を占めているが、一般に金属材料を高強度化すると、その一方で延性が低下する。そこで研究者は高強度および高延性を両立させる金属材料の開発を目指している。ハイエントロピー合金には、従来合金には見られない特異で優れた機械的特性を示すものが多く見られます。本研究は、第一原理計算、熱力学計算と実験を融合することで、ハイエントロピー合金の開発および力学特性を向上する指針を明らかにした。積層欠陥エネルギーの低下と格子歪みの増加により、高強度と高延性の両立を可能にした。今後の次世代高性能金属材料開発設計に大きく寄与するものであると考える。
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