Micromechanical origin of the enhanced ductility in twinless duplex Mg–Li alloy
Micromechanical origin of the enhanced ductility in twinless duplex Mg–Li alloy
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DOI：
10.1016/j.msea.2021.141305
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发表时间：
2021-04
期刊：
影响因子：
6.4
通讯作者：
D. Xie;Z. Lyu;M. Fan;H. Chew;P. Liaw;H. Bei;Zhongwu Zhang;Yanfei Gao
中科院分区：
文献类型：
--
作者：
D. Xie;Z. Lyu;M. Fan;H. Chew;P. Liaw;H. Bei;Zhongwu Zhang;Yanfei Gao
与许多表现出有限延展性的镁合金不同，双相Mg-Li合金具有增强的延展性，但潜在的机制尚不清楚。使用实时原位中子衍射测量，我们表明这种双重显微结构中的潜在变形模式包括体心立方（BCC）β-Li相的早期屈服和随后在大宏观塑性应变下该相的硬化升高，以及<a>六方密排（HCP）α-Mg相中基底和锥体滑移系的顺序激活。后者解除了Mises约束的变形协调性，和连续的屈服序列促进了整体加工硬化率，这两个都是有益的延性增强。在±1%的应变范围内，没有发现明显的孪晶活动，相应地，在一个完整的加载循环后，磁滞回线是对称的。
Unlike many Mg alloys that exhibit limited ductility, duplex Mg–Li alloys possess enhanced ductility but the underlying mechanisms are unclear. Using real-time in situ neutron diffraction measurements, we show that the underlying deformation modes in this duplex microstructure include an early yield of body-centered-cubic (BCC) β-Li phase and the later elevated hardening in this phase at large macroscopic plastic strain, and the sequential activation of basal and pyramidal <a> slip systems in hexagonal-close-packed (HCP) α-Mg phase. The latter relieves the Mises constraint for deformation compatibility, and the successive yielding sequence promotes the overall work hardening rate, both of which are beneficial for ductility enhancement. No obvious twinning activities were found and correspondingly the hysteresis loops were symmetric upon a full loading cycle within ±1% applied strain.