2023 Fiscal Year Research-status Report
Fatigue Characterization of Ultrahigh Strength and Ductile Mg-Gd-Y-Zn-Zr Alloy with Hierarchical Anisotropic Nanostructure
| Project/Area Number |
22KF0310
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| Allocation Type | Multi-year Fund |
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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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| Keywords | Mg-RE alloy / Very-high-cycle fatigue / Nano-precipitates / Crack nucleation / Damage accumulation |
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| Outline of Annual Research Achievements |
We investigated the very high cycle fatigue behavior of a long-period stacking ordered (LPSO) strengthened Mg alloy under both solution and aging conditions. The main microstructural difference between the two conditions is characterized by dense β' nano-precipitates under the aging condition. The fatigue strengths are comparable under both conditions, whereas the fatigue lives tend to be improved apparently under the aging condition. The improved fatigue lives under the aging condition are attributed to the dense β' nanoprecipitates, which delay the processes of crack initiation and early propagation. Plastic localization shows a continuous pattern along the damage bands under the solution condition, while it shows a scattered pattern along the damage bands under the aging condition due to the effect of β' nano-precipitates, which affect the fatigue crack nucleation mechanism.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
As planned, macroscopic fatigue properties and damage localizations under solution and aging conditions have been investigated on the LPSO-strengthened Mg alloy. The results obtained have been submitted to the journal of Materials Science & Engineering A and International Journal of Fatigue. Further research will be conducted to improve the macroscopic fatigue properties through regulating the microstructure via heat treatment. On the whole, we have achieved the research goals set up for FY2023, and the progress of the project was partially advanced.
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| Strategy for Future Research Activity |
Stacking faults (SFs) enhance non-basal dislocation sources in magnesium, addressing its ductility challenges. Therefore, we are interested in the fatigue response of the SFs-strengthened Mg alloy. We will systematically engineer two types of Mg alloy with the same laminated nanostructures: one with profuse SFs and one with dense LPSO lamellae. This will enable a comparative investigation of the fatigue response between the SFs-strengthened Mg and the LPSO-strengthened Mg. We are interested in which is more effective in enhancing the fatigue properties, and the corresponding fatigue mechanisms.
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