| Project/Area Number |
16K06706
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Physical properties of metals/Metal-base materials
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| Research Institution | Ehime University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
阿部 英司 東京大学, 大学院工学系研究科(工学部), 教授 (70354222)
大藤 弘明 愛媛大学, 地球深部ダイナミクス研究センター, 教授 (80403864)
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000)
Fiscal Year 2018: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2017: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2016: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
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| Keywords | マグネシウム合金 / 長周期積層構造 / 高圧 / 高圧合成 / 長周期構造 / Mg合金 |
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| Outline of Final Research Achievements |
Long-period stacking ordered structure synchronized with chemical concentration (LPSO) has been receiving a lot of attention as a new kind strengthening phase of materials. Mg85Zn6Y9 alloy takes 18R-type LPSO, however 18R-LPSO in the alloy can convert to duplex phase consists of hcp and fcc composed of Mg and Mg-Zn-Y, respectively. In this research, the formation process of LPSO from the duplex Mg85Zn6Y9 alloy. The fcc started to collapse and then hcp lattice expanded. After that hcp lattice started to collapse and then 18R-type LPSO emerged. Based on this result and the first principle calculation results, the formation process of LPSO was discussed.
Further, we have attempted the search of LPSO related structure by means of high-pressure synthesize of Mg97Zn1Yb2 alloy. The alloy does not take LPSO at 0.1 MPa and atomic size of Yb is slightly larger than RE included LPSO. As the result, LPSO does not form, but two kind novel long-period superlattices were discovered.
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| Academic Significance and Societal Importance of the Research Achievements |
長周期積層構造(LPSO)を含むMg合金は強度に優れ、次世代の航空機材料として期待される。Mgに金属元素と希土類（Y or ランタノイド）を添加した三元系において、LPSOは形成されるが形成メカニズムは不明である。本研究ではMgのhcp格子が膨張しLPSOへの相転移が開始されることが明らかになった。第一原理計算と併せて考えると、Mg固有の特性であるhcpと18R構造のエネルギー差が小さいことに本相転移は由来する。また、LPSOと同様に塑性異方性の高い構造をMg-Zn-Ybへの高温高圧処理にて探索したところ、二種の新奇な長周期構造が発見された。これらは高強度合金の開発に有用な知見である。
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