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Crack initiation and propagation mechanisms of an extruded dual-phase Magnesium-Lithium alloy in very high cycle fatigue regime
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  • Xiangyu WANG,
  • Chao HE,
  • Xue LI,
  • YongJie Liu,
  • Qingyuan Wang,
  • Hong ZHANG,
  • Lang LI,
  • Chong Wang
Xiangyu WANG
Sichuan University
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Chao HE
Sichuan University
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Xue LI
Sichuan University
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YongJie Liu
Sichuan University
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Qingyuan Wang
Sichuan University
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Hong ZHANG
Sichuan University
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Lang LI
Sichuan University
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Chong Wang
Sichuan University
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Abstract

Ultra-light Mg-Li alloy is a promising alloy in aerospace since it is known to the lightest structural alloy at present, but its fatigue behaviors remain to be explored. This work focuses on very-high cycle fatigue (VHCF) strength and small crack initiation behaviors of an extruded dual-phase Mg-Li alloy (LZ91). The fatigue strength of the LZ91 alloy at 109 cycles is about 78 MPa, and the fatigue ratio is approximately 0.46. Microstructure characterization demonstrates that fatigue crack tends to initiate from the β-Li phase-enriched region. The α-Mg phase, presenting <10−10 >  fiber texture with the basal plane, deforms hardly along the extrusion direction and acts as an enhanced phase compared with the β-Li phase. The deformation discrepancy localizes cyclic plasticity at the Li phase and finally leads to the fatigue crack initiation.

Peer review status:UNDER REVIEW

21 Apr 2021Submitted to Fatigue & Fracture of Engineering Materials & Structures
22 Apr 2021Assigned to Editor
22 Apr 2021Submission Checks Completed
27 Apr 2021Reviewer(s) Assigned
24 May 2021Review(s) Completed, Editorial Evaluation Pending