Plastic contribution via DRX induced by kink and twin in a hot compressed Mg-Gd-Zn-Mn alloy with 14H LPSO

Abstract

The plastic deformation behavior in Mg alloy with long period stacking ordered phases (LPSO) has not fully understood yet. To understand the interaction between twins, kink and dynamic recrystallization in a Mg alloy with long period stacking ordered phases, the plastic forming behavior under compression at elevated temperatures of the Mg-4Gd-1Zn-0.5Mn alloys containing lamellar long period stacking order phases were investigated. The lamellar long period stacking ordered phases hindered the occurrence of grain boundary migration, thus delaying dynamic recrystallization. The dominated deformation mechanisms of the compressed alloy were slip and discontinuous dynamic recrystallization accompanied by the occurrence of kink bands at low deformation rates. The twinning was the domination deformation mechanisms of the alloy at high deformation rates, a few recrystallized grains distributed along the boundaries of the twins and it was an obvious twin-induced dynamic recrystallization mechanism. The dissolving of long period stacking ordered phases reduced the grain boundary migration resistance of dynamic recrystallization and thus promoted the nucleation of the recrystallized grains at 500 °C. The broken small-sized lamellar long period stacking ordered phases became effective heterogeneous nucleation sites and thus promoted DRX. The parallel and beak-like kink bands are clearly observed in the microstructures of the deformed alloys. The severe kink behavior improves the plastic formability of the alloy.