Activation of multiple twins by pre-tension and compression to enhance the strength of Mg-3Al-1Zn alloy plates

For basal textured Mg alloy plates, {10-12} twins can be easily generated by pre-compression perpendicular to the c-axis of grains. Thus, it should be practical to strengthen Mg alloy plates by introducing twin boundaries. In this study, we show that control of the a-axis distribution is also important for enhancing the strengthening effect by pre-inducing {10-12} twins. Pre-tension along rolling direction (RD) is applied on a rolled AZ31 Mg alloy plate, and then the sample is compressed along transverse direction (TD) to generate {10-12} twins. The experimental results show that pre-tension causes 〈10-10〉 orientations concentrating toward RD, which promotes the activation of multiple twin variants in each grain for subsequent compression along TD. As a consequence, twin nucleation rather than twin growth is favored, and the number of twin lamellae per grain is increased, which enhances the refinement hardening effect during compression of the twinned sample along RD. The underline mechanism is analyzed, which can also provide some insights into understanding deformation mechanism of Mg alloys.