Improving the high-temperature mechanical properties of a magnesium alloy by equal-channel angular pressing

Equal-channel angular pressing (ECAP) was conducted on a Mg–0.55% Zr alloy at a temperature of 513 K. It is shown that processing by ECAP refines the grain size from ∼75 to ∼8.6 μm. Tensile testing was performed at temperatures from 473 to 773 K and at initial strain rates from 10−5 to 10−2 s−1 using specimens in the as-received condition and after processing by ECAP through six passes. There is a higher strength in the as-received Mg–Zr alloy than in the Mg–Zr alloy after ECAP for six passes at a temperature of 513 K. The results show the tensile elongations are higher after ECAP and a maximum elongation of ∼380% was achieved in the as-pressed material at 773 K using an initial strain rate of 4.2 × 10−5 s−1. The strain rate sensitivity for the as-pressed alloy was estimated as ∼0.17 and the activation energy were intermediate between the values for grain boundary and lattice diffusion in magnesium.