Effect of homogenization on the hot-deformation ability and dynamic recrystallization of Mg–9Gd–3Y–0.5Zr alloy

Two states of Mg–9Gd–3Y–0.5Zr (wt.%) (GW93) alloy, as-cast (note as F state) and homogenized (note as T4 state), were hot compressed at strain rate of 0.1 s−1 and temperatures range from 623 K to 723 K. The stress-strain curves were established and volume fractions of dynamic recrystallized (DRX) grains were determined using point counting method. The results show that flow stresses are sensitive to the compression temperature and pretreatment state. Comparing with as-cast alloy, T4 state alloy has a higher flow stress and strain hardening rate θ, more complicated deformation microstructures, a smaller dynamic recrystallization rate and Avrami exponents. The phenomena are the results of the difference of initial nucleation sites and eutectic particles stimulated nucleation (EPSN) of two states. The initial nucleation sites of as-cast alloy include the original grain boundaries and eutectic particles, but as for T4 alloy, only original coarse grain boundaries can be act as nucleation sites.