| Project/Area Number |
18H01340
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Basic Section 18010:Mechanics of materials and materials-related
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| Research Institution | Oita University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
薬師寺 輝敏 大分工業高等専門学校, 機械工学科, 教授 (90210228)
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| Project Period (FY) |
2018-04-01 – 2022-03-31
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| Project Status |
Completed (Fiscal Year 2021)
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| Budget Amount *help |
¥17,680,000 (Direct Cost: ¥13,600,000、Indirect Cost: ¥4,080,000)
Fiscal Year 2021: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
Fiscal Year 2020: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
Fiscal Year 2019: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
Fiscal Year 2018: ¥10,660,000 (Direct Cost: ¥8,200,000、Indirect Cost: ¥2,460,000)
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| Keywords | 銅合金 / 不連続析出 / 疲労 / 組織 / 強変形加工 / 微細化 / 析出強化銅合金 / き裂 |
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| Outline of Final Research Achievements |
In general, Cu-Ni-Si alloy is used after aging that produces nanosized Ni2Si precipitates to give the alloy maximum hardness. The crack initiation site of aged alloy was grain boundaries (GBs), this is because of the formation of precipitate-free zone along GBs and coarse precipitates at GBs. After over aging, fiber-shaped precipitates were grew within the original grains (grains before aging). The overaged alloy has higher conductivity and lower tensile strength than aged one, and there was no deference in fatigue strength at 107 cycles between aged and overaged alloys. The starting point of fatigue crack of overaged alloy was original GBs. The overaged alloy with severe plastic deformation (80% cold rolling) exhibited 1.6, 1.05 and 1.5 times of conductivity (IACS), tensile strength and fatigue strength at 107 cycles of the aged alloy, respectively. Fatigue crack initiation and propagation mechanism of ultrafine grain copper fabricated by severe plastic deformation were clarified.
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| Academic Significance and Societal Importance of the Research Achievements |
電気電子部品の小型軽量化，高集積化，高効率化の要求から，その素材となる銅合金の特性向上が望まれている．銅合金の開発は，加工熱処理条件と添加元素の工夫を通して行われているが，強度が向上すれば導電性は低下する問題がある（二律背反的）．また，実際の電気電子部品は使用中の繰返し応力，通電や使用環境による熱ひずみを受け，耐疲労特性が要求される．本研究成果は，普通は使用されない過時効材の組織を改変することで強度と導電性の優れた素材が得られることを示し今後の銅合金の開発の道を開いた．また，強変形された組織を調べ，これまで不明であった超微細粒材料の疲労損傷の形成メカニズムを解明したことは学術的に意義が有る．
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