Accounting for the effect of dislocation climb-mediated flow on the anisotropy and texture evolution of Mg alloy, AZ31B
Accounting for the effect of dislocation climb-mediated flow on the anisotropy and texture evolution of Mg alloy, AZ31B
复制标题
DOI：
10.1016/j.msea.2021.142581
复制
发表时间：
2021-12
期刊：
影响因子：
--
通讯作者：
M. Ritzo;R. Lebensohn;L. Capolungo;S. Agnew
中科院分区：
文献类型：
--
作者：
M. Ritzo;R. Lebensohn;L. Capolungo;S. Agnew
目前的研究探索了位错攀移在中等高温下调节镁合金塑性的作用。对AZ31B镁合金板材在O回火条件下进行了沿轧制和横向应变速率(10-5~10-1s-1)和温度(20-350℃)范围内的断续拉伸试验。在采用新的晶体塑性模型(VPSC-SCRADE)进行参数研究时，以应变各向异性和织构演化的实验测量为约束条件，该模型显式地解释了位错攀移的运动学。结果表明，基面位错的攀移不仅对位错回复是重要的，而且在幂定律蠕变本构响应占优势的条件下，攀移可以容纳相当一部分的应变。这项工作并没有推翻这样的观点，即在广泛的温度和应变率范围内，和&c+a>；位错的非基滑移是重要的。然而，它证明了位错攀移的激活是由于幂定律区域内的机制变化，这为广泛的观测提供了解释，包括应变各向异性的同时降低，织构演化的减慢，以及应变率敏感性的快速增加。最后，假设这些结论甚至适用于观察到晶界滑移和/或动态再结晶的情况。
The current study explores the role that dislocation climb has in mediating plasticity a Mg alloy at moderately elevated temperatures. Interrupted tensile tests were performed on samples of Mg alloy, AZ31B, sheet in the O temper condition over a range of strain rates (10-5to 10-1s-1) and temperatures (20–350°C) along the rolling and transverse directions. Experimental measurements of the resulting strain anisotropy and texture evolution were used as constraints during a parametric study employing a new crystal plasticity model (VPSC-CLIMB), which explicitly accounts for the kinematics of dislocation climb. The results reveal that the climb of basal dislocations is not only important for dislocation recovery, but also demonstrate that climb accommodates a significant fraction of the strain in conditions where a power-law creep-type constitutive response prevails. This work does not discredit the notion that non-basal slip of and <c+a> dislocations is important over a wide range of temperatures and strain rates. However, it demonstrates that the activation of dislocation climb as the mechanistic change within the power law regime provides an explanation for a wide range of observations, including the simultaneous reduction in strain anisotropy, slowed texture evolution, and rapid increase in strain rate sensitivity. Finally, it is hypothesized that these conclusions may even apply to cases in which grain boundary sliding and/or dynamic recrystallization are observed.