2023 Fiscal Year Final Research Report
Study on influence of twin deformation to fatigue crack initiation of Mg alloy using ultra-bright synchrotron radiation 4D-DCT
| Project/Area Number |
18K03837
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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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| Review Section |
Basic Section 18010:Mechanics of materials and materials-related
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| Research Institution | Kobe University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
塩澤 大輝 神戸大学, 工学研究科, 准教授 (60379336)
菊池 将一 静岡大学, 工学部, 准教授 (80581579)
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| Project Period (FY) |
2018-04-01 – 2024-03-31
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| Keywords | マグネシウム合金 / 双晶変形 / 双晶消滅 / 集合組織 / 高輝度放射光 / トモグラフィー |
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| Outline of Final Research Achievements |
In the textured material, cyclic loading showed that twinning occurred only under compressive stress, and all twinning disappeared under subsequent tensile stress. In some cases, the twinning bands and their disappearance were reversible, while in other cases, they were irreversible. On the other hand, in the randomly oriented material, twinning bands occurred under both tensile and compressive stresses, and the twinning bands that occurred under compressive stress did not disappear under subsequent tensile stress loading. Furthermore, after repeated cyclic compression-compression loading that did not cause twinning, the normal (c-axis) of the bottom surface changed to an aggregate structure with the loading axis aligned in the direction of the loading axis.
Diffraction contrast tomography using high-brilliance synchrotron radiation was used to measure the misorientation β. The relationship between the change in β, deformation, and twinning was clarified.
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| Free Research Field |
18010
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| Academic Significance and Societal Importance of the Research Achievements |
Mg合金は，結晶のすべりだけでなく双晶変形を生じなければ，塑性変形できないことが知られている．しかしながら，高サイクル疲労においては，すべり易い方位を持った結晶粒のみがすべり変形を起こし，大部分の結晶粒は塑性変形しなくても，疲労き裂が発生することを明らかにしたことが本研究の学術的意義である．
一方，地球温暖化対策として，自動車を始めとした各種輸送機器に，金属材料中で最も比強度が高いMg合金を積極的に活用し，車体を軽量化することによって省エネルギー化することが必要である．本研究では，Mg合金の疲労破壊機構を解明することによって，Mg合金を用いた輸送機器の強度保証をするための基本的な指針が得られた．
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