| Project/Area Number |
22KF0310
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| Project/Area Number (Other) |
22F22720 (2022)
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| Research Category |
Grant-in-Aid for JSPS Fellows
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| Allocation Type | Multi-year Fund (2023)
Single-year Grants (2022) |
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| Section | 外国 |
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| Review Section |
Basic Section 18010:Mechanics of materials and materials-related
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| Research Institution | Kyushu University |
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Principal Investigator |
陳 強 九州大学, 工学研究院, 教授 (30264451)
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| Co-Investigator(Kenkyū-buntansha) |
CHEN YAO 九州大学, 工学研究院, 外国人特別研究員
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| Project Period (FY) |
2023-03-08 – 2025-03-31
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| Project Status |
Completed (Fiscal Year 2024)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 2024: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2023: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2022: ¥500,000 (Direct Cost: ¥500,000)
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| Keywords | Mg-RE alloy / Very-high-cycle fatigue / Heat treatment / β' nano-precipitates / Damage accumulation / Nano-precipitates / Crack nucleation / Very high cycle fatigue / Crack initiation / Oxidation / Oxygen embrittlement |
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| Outline of Research at the Start |
The proposed research is to undertake quasi-in situ fatigue observation to characterize fatigue transitions from a crack-free stage to a cracked stage, and further short crack growth stage. This study aims at revealing dislocation structures associated with nucleation of microcracks and connecting atomic scale deformation with macroscopic fatigue performance.
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| Outline of Annual Research Achievements |
For the beta prime nanoprecipitates and LPSO co-strengthened Mg-RE alloy, unique oxide nodules are observed as a type of fatigue damage that facilitates crack initiation, differing from typical slip-band structures. The presence of LPSO lamellae and dense distributed beta prime nano-precipitates contributes to the high localization of fatigue damage in the form of oxide nodules. These fatigue-induced oxide nodules form and expand within the soft alpha-Mg layer, but their growth is constrained by the surrounding strong LPSO lamellae, resulting in microcrack nucleation. Ultimately, clusters of microcracks along the LPSO/oxide interface merge along the damage bands, leading to the trans-granular crack initiation. Due to the synergistic effect of the LPSO lamellae and the dense beta prime nanoprecipitates, the fatigue life is accordingly prolonged compared to the LPSO-strengthened Mg-RE alloy. The findings offer valuable insights into the potential for designing and modifying microstructures to enhance the fatigue performance of Mg-RE alloys.
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