Hot deformation behavior and microstructure evolution of a Mg-Gd-Nd-Y-Zn alloy

The hot deformation behavior of homogenized Mg-6.5Gd-1.3Nd-0.7Y-0.3Zn alloy was investigated during compression at temperatures of 250-400 degrees C and at strain rates ranging from 0.001 to 0.100 s(-1). Microstructure analyses show that the flow behaviors are associated with the deformation mechanisms. At the lower temperatures (250-300 degrees C), deformation twinning is triggered due to the difficult activation of dislocation cross-slip. Dynamic recrystallization (DRX) accompanied by dynamic precipitation occurs at the temperature of 350 degrees C and influences the softening behavior of the flow. DRX that develops extensively at original grain boundaries is the main softening mechanism at the high temperature of 400 degrees C and eventually brings a more homogeneous microstructure than that in other deformation conditions. The volume fraction of the DRXed grains increases with temperature increasing and decreases with strain rate increasing.