Deformation twinning and detwinning in extruded Mg-4Al were investigated using in-situ SEM-DIC experiments and crystal plasticity finite element (CPFE) simulation. In this study, the in-situ SEM-DIC method was used to provide a unique set of data including twin/detwin characteristics and twin area fraction in addition to strain maps. A statistical analysis of the activation of twin variants and twin area fraction during both twinning and detwinning was conducted. A strong correlation was found between twin growth/shrinkage and the Schmid Factor (SF) for individual twin variants Higher twin SF during loading and unloading led to higher twin growth and shrinkage, respectively. However, after the applied compressive strain was removed, the pattern of the twin area fractions of the residual twin variants versus their nominal SFs did not follow the trend observed at the maximum compressive strain. Using a systematic methodology and an advanced twin/detwin model, the PRISMS-Plasticity CPFE simulation was calibrated using experimentally determined stress versus strain and twin area fraction versus strain information. A comprehensive evaluation of the CPFE model was conducted to determine its ability to capture the statistics of twin variants activation and twin area fraction. CPFE accurately captured the statistical aspects of both twinning and detwinning. It also predicted the first dominant twin variant for 47.5% of the grains and at least one of the two dominant twin variants for 80% of the grains at maximum compressive strain.

使用原位SEM-DIC 实验和晶体塑性有限元 (CPFE) 模拟研究了挤压 Mg-4Al 中的变形孪晶和去孪晶。在本研究中，原位SEM-DIC 方法用于提供一组独特的数据，包括孪晶/去孪晶特征和孪晶面积分数以及应变图。对孪生和去孪生期间孪生变异体的激活和孪生面积分数进行了统计分析。发现双胞胎生长/收缩与单个双胞胎变体的施密德因子 (SF) 之间存在很强的相关性，加载和卸载期间双胞胎 SF 越高，双胞胎生长和收缩率越高。然而，在去除施加的压缩应变后，剩余孪晶变体的孪晶面积分数与其标称 SF 的模式并没有遵循在最大压缩应变下观察到的趋势。使用系统的方法论和先进的孪生/去孪生模型，PRIMSMS-Plasticity CPFE 模拟使用实验确定的应力与应变和孪晶面积分数与应变信息进行校准。对 CPFE 模型进行了全面评估，以确定其捕获孪生变体激活和孪生面积分数的统计数据的能力。CPFE 准确地捕捉了孪生和去孪生的统计方面。它还预测了 47.5% 的晶粒的第一个主要孪晶变体和 80% 的晶粒在最大压缩应变下的两个主要孪晶变体中的至少一个。CPFE 准确地捕捉了孪生和去孪生的统计方面。它还预测了 47.5% 的晶粒的第一个主要孪晶变体和 80% 的晶粒在最大压缩应变下的两个主要孪晶变体中的至少一个。CPFE 准确地捕捉了孪生和去孪生的统计方面。它还预测了 47.5% 的晶粒的第一个主要孪晶变体和 80% 的晶粒在最大压缩应变下的两个主要孪晶变体中的至少一个。