2022 Fiscal Year Final Research Report
The microscopic origin of phase stability and role of solute atoms in metal alloys having partial dislocation; A first-principles study
Project/Area Number |
19K04988
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Research Category |
Grant-in-Aid for Scientific Research (C)
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Allocation Type | Multi-year Fund |
Section | 一般 |
Review Section |
Basic Section 26010:Metallic material properties-related
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Research Institution | Kumamoto University |
Principal Investigator |
Tsumuraya Takao 熊本大学, 先進マグネシウム国際研究センター, 准教授 (00619869)
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Project Period (FY) |
2019-04-01 – 2023-03-31
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Keywords | マグネシウム合金 / LPSO / 原子空孔 / Convex Hull / 電子状態 / 第一原理計算 / 形状記憶合金 / マルテンサイト変態 |
Outline of Final Research Achievements |
We studied the origin of the phase stability of pure-Fe and Mg-Zn-Y based alloys with long-period stacking order (LPSO) using first-principles density-functional theory (DFT) calculations. We showed how the electronic structure near the Fermi level affects the structural stability in both systems. To understand the actual stacking pattern and to discuss the possible realization of an LPSO phase as the intermediate phase between the γ and ε phases, the magnetic phase stability of various LPSO structures of pure-Fe was examined. We also discuss the origin of the phase stability of 18R Mg-Zn-Y alloys with a LPSO using first-principles DFT calculations. We calculate the heat of formation as a function of the number of Zn vacancies to discuss the role of Zn atoms. The convex hull indicates that the Zn atoms in the LPSO alloys are stable even if they number about half of the Y atoms. The bonding state with Zn p orbitals leads to the stability of the LPSO structure.
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Free Research Field |
第一原理計算
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Academic Significance and Societal Importance of the Research Achievements |
電子顕微鏡やアトムプローブを用いて複雑な組織や面・点欠陥が介在した材料系における電子相や界面での原子の振る舞いが直接観察できるようになっており, 本研究で得られた原子空孔の安定性といった準安定状態に関する情報と実験結果を対応させることで材料特性の発現の素過程を演繹できる可能性が格段に高まっている。今後、本研究で予測された準安定構造に対する弾性係数や積層欠陥エネルギーに関する第一原理計算を実施することで、結晶塑性FEM等のマクロな計算手法との連携を可能にし、スケール間連携による力学特性の素過程の解明に迫っていきたい。
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