Compressive deformation of Mg–Zn–Y–Zr alloy processed by equal channel angular pressing

Abstract: An ultrafine-grained (UFG) Mg–Zn–Y–Zr magnesium alloy with a grain size of about 0.8μm was produced by subjecting the extruded alloy to equal channel angular pressing (ECAP) for eight passes at 473K. Compressive testing was performed on the as-extruded and on the further ECAP-processed Mg–Zn–Y–Zr alloy at a temperature of 423K and under strain rates from 1.67×10−3 to 1.67×10−1 s−1. In the UFG ECAP-processed magnesium alloy, the strain hardening rate was extremely low, in contrast to that of the extruded alloy. The ultrafine grains of the ECAP-processed alloy were stable in compression because of the presence of the dispersion of a fine I-phase and of precipitates in the alloy, which restricted grain growth. The ECAP-processed alloy exhibited a higher strain rate sensitivity exponent than the as-extruded magnesium alloy, which may have contributed to its enhanced ductility. [Copyright &y& Elsevier]