2019 Fiscal Year Final Research Report
Formulation of a comprehensive solid-solution-strengthening theory accounting for short-range-order softening
| Project/Area Number |
18K18936
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Review Section |
Medium-sized Section 26:Materials engineering and related fields
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| Research Institution | Tohoku University |
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Principal Investigator |
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| Project Period (FY) |
2018-06-29 – 2020-03-31
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| Keywords | 固溶強化 / 原子変位 / 降伏強度 / 固溶体合金 |
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| Outline of Final Research Achievements |
The degree of solid solution strengthening in some high-entropy alloys and binary solid-solution alloys is positively correlated with the average atomic displacement of the constituent elements from the ideal lattice points. However, some binary alloys with short-range ordering are negatively deviated from the linear relationship between the degree of solid solution strengthening and the average atomic displacement derived by assuming a random solid solution, inferring that the short-range order softening could occur in those alloys unlike the traditional short-range order strengthening. We clarified that the degree of short-range ordering strongly affects the average atomic displacement by systematically performing first-principles structural relaxation, and explained the apparent short-range order softening phenomena in some binary solid solution alloys in view of the change in the average atomic displacement due to the short-range ordering.
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| Free Research Field |
金属材料，金属物性
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| Academic Significance and Societal Importance of the Research Achievements |
身の回りの金属材料のほとんどは，純金属ではなく異種元素が原子レベルで混ざった(固溶体)合金です．異種元素が固溶することによって合金の強度がどの程度高くなるか(固溶強化量)に関して，古くから理論的研究がされてきましたが，単純な合金系や固溶元素濃度が低い場合にしか適用できません．研究代表者らは，固溶強化量を予測し得るユニバーサルな指標として構成元素の結晶格子位置からのずれ(原子変位量)を提案してきましたが，本研究では固溶元素がランダム配列している場合だけでなく，特定の優先的配列をした場合にも固溶強化量の予測指標となりうることを示しました．
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