In this study, the twinning–detwinning behavior and slip behavior of rolled AZ31 magnesium-alloy plates during a three-step intermittent dynamic compression process along the rolling direction (RD) and normal direction (ND), are investigated via quasi-in situ electron backscatter diffraction, and the causes of the twinning and detwinning behavior are explained according to Schmid law, local strain coordination, and slip trajectories. It is found that the twins are first nucleated and grow at a compressive strain of 3% along the RD. In addition to the Schmid factor (SF), the strain coordination factor (m') also influences the selection of the twin variants during the twinning process, resulting in the nucleation of twins with a low SF. During the second and third steps of the application of continuous compressive strains with magnitudes and directions of 3%RD+3%ND and 3%RD+3%ND+2.5%ND, detwinning occurs to different extents. The observation of the detwinning behavior reveals that the order in which multiple twins within the same grain undergo complete detwinning is related to Schmid law and the strain concentration, with a low SF and a high strain concentration promoting complete detwinning. The interaction between slip dislocations and twin boundaries in the deformed grains as well as the pinning of dislocations at the tips of the {10$\overline{1}$$\overline{1}$2} tensile twins with a special structure result in incomplete detwinning. Understanding the microstructural evolution and twinning behavior of magnesium alloys under different deformation geometries is important for the development of high-strength and high-toughness magnesium alloys.

中文翻译：

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AZ31镁合金轧制板在不同方向压缩载荷作用下的孪晶-双晶行为准原位电子背散射衍射分析


本研究通过准原位电子背散射衍射研究了轧制AZ31镁合金板在沿轧制方向（RD）和法向（ND）的三步间歇动态压缩过程中的孪晶-去孪生行为和滑移行为，并根据施密德定律、局部应变配位、 和滑移轨迹。发现双胞胎首先成核并沿 RD 以 3% 的压缩应变生长。除了施密德因子 （SF） 之外，应变协调因子 （m'） 也会影响孪晶过程中孪晶变体的选择，从而导致低 SF 的孪晶成核。在施加大小和方向为 3%RD+3%ND 和 3%RD+3%ND+2.5%ND 的连续压缩应变的第二步和第三步中，发生不同程度的双胞胎。对双胞胎行为的观察表明，同一晶粒内多个孪生体发生完全去孪生的顺序与 Schmid 定律和应变浓度有关，低 SF 和高应变浓度促进完全解缠。滑移位错与变形晶粒中孪晶界之间的相互作用，以及位错在具有特殊结构的 {10$\bar{1}$2} 拉伸孪晶的尖端的固定，导致不完全解缠。了解镁合金在不同变形几何形状下的微观组织演变和孪晶行为对于开发高强度和高韧性镁合金非常重要。