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

The hot deformation behavior of homogenized Mg-6.5Gd-l.3Nd4）.7Y-0.3Zn alloy was investigated during compression at temperatures of 250-400 ℃ 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 ℃）, defor- mation twinning is triggered due to the difficult activation of dislocation cross-slip. Dynamic recrystallization （DRX） ac- companied by dynamic precipitation occurs at the temperature of 350 ℃ 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 ℃ and eventually brings a more homogeneous mi- crostructure than that in other deformation conditions. The volume fraction of the DRXed grains increases with tem- perature increasing and decreases with strain rate increasing.