Effects of rare earth elements and Ca additions on high temperature mechanical properties of AZ31 magnesium alloy processed by ECAP

High temperature mechanical properties of equal channel angularly pressed (ECAPed) AZ31 magnesium alloy with 0.6%RE, 0.6%Ca and 0.3%RE-0.3%Ca additions were investigated. After extruding, the materials were ECAPed for 4 passes using route BC. Due to the textural effects induced by ECAP, the flow stress of the ECAPed AZ31 was lower than that of the extruded alloy at 523 K while tensile ductility was not changed. Thermal stability of the grain structure was achieved by RE-and Ca-containing particles, mainly due to the suppression of grain growth. Addition of the RE elements and calcium increased tensile strength mainly by dispersive strengthening effects of particles. The improved tensile ductility of the extruded material, however, was achieved by the presence of stable fine grains. Among all tested materials, AZ31-0.6%RE showed the maximum ductility of 198% at 523 K and a strain rate of 10−4 s−1.