The roles of long period stacking ordered structure and Zn solute in the hot deformation behavior of Mg-Gd-Zn alloys

Abstract

In order to investigate the roles of long period stacking ordered (LPSO) structure and Zn solute in the hot deformation behavior of Mg-Gd-Zn alloys, the Mg-12Gd-1Zn-1Mn-0.5Zr alloy containing LPSO phase or Zn solute was hot compressed under various deformation conditions in comparison with the Zn-free Mg-12Gd-1Mn-0.5Zr alloy. The results showed that the Zn-containing alloys had stronger softening effects, larger peak stress and higher average activation energy than the Zn-free one within the safe deformation domain. Both LPSO phase and Zn solute in α-Mg matrix increased the efficiency of power dissipation, narrowed down the flow stability regions of processing map and impeded the dynamic recrystallization (DRX), especially when Zn solute was mainly in α-Mg matrix. Furthermore, the LPSO phase or Zn solute in α-Mg matrix promoted the dynamic precipitation. A few Mg5Gd particles can be observed in the Zn-free alloy, while a large number of stacking faults (SFs) and LPSO phase were precipitated in the Zn-containing alloys, and they were eventually transformed into Mg5Gd particles at low strain rate.