2017 Fiscal Year Annual Research Report
ＬＰＳＯ相を有する高強度Ｍｇ－Ｚｎ－Ｙ合金の超高サイクル疲労破壊機構の解明
| Project/Area Number |
16F16809
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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) |
HE CHAO 九州大学, 工学(系)研究科(研究院), 外国人特別研究員
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| Project Period (FY) |
2016-11-07 – 2019-03-31
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| Keywords | Very High Cycle Fatigue / Magnesium Alloys / LPSO Phase / Ultrasonic fatigue |
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| Outline of Annual Research Achievements |
Fatigue behavior and fracture mechanism of Mg alloys containing LPSO phases were investigated in the regime of very high cycle fatigue to clarify the effect of LPSO phase on the crack initiation and small crack propagation process at both microscopic and atomic scales.
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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
1. Ultrasonic fatigue tests were carried out on the extruded Mg-Gd-Y alloys (GW103k), casted Mg-Gd-Y-Zn alloys and soluted Mg-Gd-Y-Zn alloys
2. Fatigue crack initiation and early propagation behaviors as well as the effect of microstructural heterogeneouty on the fatigue behavior were studied.
3. TEM observation of fatigue crack initiation sites at atomic scale was performed. A new segregation mode of rare earth elements caused by the motion of basal dislocations was found.
4. Partial results were presented at the 71th Annual Meeting of Japan Society of Mechanical Engineers and published a paper on journal of Materials Science and Technology.
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| Strategy for Future Research Activity |
By comparison of three kinds of Mg-Gd-Y-Zn-Zr alloys, the effects of LPSO phase on fatigue crack initiation and its early propagation will be clarified. The crack path and fatigue crack propagation rate will be investigated using a specially designed CT specimen. Fatigue fracture mechanism included that governs cyclic deformation in the VHCF regime will be illucidated using SEM, EBSD, FIB and HRTEM. Some critical ideas for microstructure design are expected to improve the super long life strength of Mg alloys.
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[Presentation] Small crack behavior of extruded Mg-Gd-Y-Zr alloy under high cycle fatigue2018
Author(s)
Chao HE, Xiaohong SHAO, Yoshihiro FUKUSHIMA, Kaneaki TSUZAKI, Qingyuan WANG, Ning SU, Xiangwen HENG, Qian ZHAO, Liming PENGc, Yujuan WU, Qiang CHEN
Organizer
日本機械学会 九州支部 第71期 総会・講演会
