2020 Fiscal Year Final Research Report
| Project/Area Number |
18H03753
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Medium-sized Section 18:Mechanics of materials, production engineering, design engineering, and related fields
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| Research Institution | Kyoto University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
中村 篤智 名古屋大学, 工学研究科, 准教授 (20419675)
嶋田 隆広 京都大学, 工学研究科, 准教授 (20534259)
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Keywords | Fatigue / Micro-sized metals / Tension-compression / In situ observation / Single crystal |
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| Outline of Final Research Achievements |
The purpose of this study is to investigate the mechanism of tension-compression fatigue in micro- to nano-sized pure metals. In micro-sized single-crystal copper (Cu) specimens, it was confirmed that the extrusions/intrusions grew with the increase in the number of cycles and that fatigue cracks appeared at the bottom of the intrusion. On the other hand, cyclic work hardening did not occur, and the appearance of the extrusions/intrusions was different from that of Cu bulk counterpart. Low stress amplitude tests using micro-sized single-crystal nickel (Ni) specimens showed that fatigue damage occurred even below the fatigue limit of the bulk. Experiments on specimens with different dimensions showed that the fatigue behavior changed with the change in material dimensions. Transmission electron microscopy revealed that the internal dislocation structure was strongly influenced by the surfaces of material.
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| Free Research Field |
微小材料強度学、金属結晶学
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| Academic Significance and Societal Importance of the Research Achievements |
各種半導体デバイスの内部には、ナノ～マイクロサイズの金属素子が多数存在する。これらのデバイスは、近年では自動車等の厳しい環境下で使用されるようになり、内部の金属素子の疲労破壊が問題となっている。ナノ～マイクロサイズの金属では、疲労破壊の発生原因とされる下部組織の寸法の観点から従来の金属疲労とは異なる挙動を示すことが予測されるが、その学理自体が存在しなかった。本研究では、その学理の基礎基盤の礎を構築することに成功しており、学術的意義や社会的意義は極めて大きい。
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