Contribution of extension twinning to plastic strain at low stress stage deformation of a Mg-3Al-1Zn alloy
Contribution of extension twinning to plastic strain at low stress stage deformation of a Mg-3Al-1Zn alloy
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DOI：
10.1016/j.msea.2017.10.038
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发表时间：
2018-01-02
期刊：
影响因子：
6.4
通讯作者：
Jiang, Y.
中科院分区：
文献类型：
--
作者：
Chen, P.;Li, B.;Jiang, Y.
挤压态镁合金在沿着挤压方向压缩时，由于{10（1）过棒2}（10（11）过棒）拉伸孪晶的激活，呈现出典型的S形应力-应变曲线。在低应力变形阶段，孪晶对塑性应变的贡献的定量测量在文献中是不完整的。本文利用电子背散射衍射技术对挤压态Mg-3Al-1 Zn合金在低应力阶段塑性变形过程中孪晶体积分数的变化进行了细致的测量，并计算了孪晶对塑性应变的贡献。结果表明，在屈服初期，位错滑移是塑性应变的主要贡献者，但孪晶形核已经被激活。随着塑性应变的增加，孪晶的贡献迅速增加。当塑性应变超过1.0%时，延伸孪晶贡献80-90%的塑性变形，直到孪晶饱和。
Extruded magnesium alloys present a typical sigmoidal shaped stress-strain curve when compressed along the extrusion direction due to the activation of {10 (1) over bar2}(10 (11) over bar) extension twinning. Quantitative measurements of the contribution of twinning to plastic strain at the low stress stage deformation are incomplete in the literature. In this work, we carefully measured the evolution of twin volume fraction during low stress stage plastic deformation of an extruded Mg-3Al-1Zn alloy by electron bacicscatter diffraction, and calculated the contribution of twinning to the plastic strain. Our results show that, at the very beginning of yielding, basal dislocation slip is the main contributor to the plastic strain, but twin nucleation is already activated. The contribution from twinning rapidly increases as the plastic strain increases. After the plastic strain exceeds 1.0%, extension twinning contributes 80-90% of the plastic deformation until twinning is saturated.