Dynamic compression properties and microstructural evolution of ZCW612 alloy under different strain levels

In this study, a novel Mg-6Zn-1Cu-2Y-0.6Zr (ZCW612) magnesium alloy is prepared using a hot extrusion-shearing process. The mechanical properties, microstructural evolution, and deformation mechanisms of the extruded ZCW612 alloy under dynamic compression are studied at different temperatures (25 °C, 100 °C, 200 °C, 300 °C) and strain levels (3%, 6%, 8%, 12%) along the extrusion direction (ED). The experimental results show that the initial extruded alloy has an apparent (0001) basal texture and an average grain size of 4.5 µm. Meanwhile, the alloy consists mainly of α-Mg, MgZnCu phase, and Mg3Y2Zn3 phase. During dynamic compression at a strain rate of 2000 s−1, the peak stress of the ZCW612 alloy decreases with increasing temperature. The deformation mechanisms of the ED samples are mainly basal slip, pyramidal slip, and extension twinning. In addition, dynamic recrystallisation and low-angle grain boundaries resulting from the accumulation of a large amount of dislocations in grains are induced, leading to grain refinement of the ZCW612 alloy after dynamic deformation. At the same time, after dynamic compression at 300 °C, a certain degree of grain growth occurs in the ED samples due to grain boundary migration.