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

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 similar to 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 similar to 1230% at strain rate of 10(-2) s(-1) and at two temperatures: 350 degrees C and 400 degrees C. Increase in the strain rate to 10(-1) s(-1) resulted in maximum elongation of similar to 1000% at the temperature of 400 degrees 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 degrees 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.