Excellent superplastic properties achieved in Mg–4Y–3RE alloy in high strain rate regime

Abstract

This study is focused on high strain rate superplasticity of commercial magnesium alloy Mg–4Y–3RE (WE43) in ultrafine-grained condition prepared by equal channel angular pressing (ECAP). Attaining microstructure with the average grain size of ~340 nm and high density of secondary phase particles provided a possibility to significantly decrease temperature during the deformation at strain rates of 10−2 s−1 and 10−1 s−1 in comparison with previous studies. Consequently, extent of negative effect of grain growth was partially suppressed and the investigated alloy did exhibit exceptionally high deformability with a maximum elongation of ~1230% at strain rate of 10−2 s−1 and at two temperatures: 350 °C and 400 °C. Increase in the strain rate to 10−1 s−1 resulted in maximum elongation of ~1000% at the temperature of 400 °C. The microstructural analysis after the deformation showed that the microstructure was fine-grained even after large deformation and plasticity-controlled growth of cavities did occur only at the temperature of 450 °C. The optimization of ECAP processing resulted in very weak texture and, therefore, the deformability should be more isotropic in comparison with strongly textured materials usually investigated in this regard.