Hot compression behavior and microstructure evolution of Mg-Gd-Y-Zn-Zr alloy

Abstract

In this work, the hot compression behavior and microstructure evolution of Mg-8Gd-3Y-xZn-0.6Zr (x = 0, 1.5) alloys were investigated by Gleeble-1500D thermal simulation test machine, SEM, EBSD and other equipment. The results showed that, prior to hot deformation, the grain size of Mg-8Gd-3Y-1.5Zn-0.6Zr (1.5Zn) alloy was smaller than that of Mg-8Gd-3Y-0.6Zr (0Zn) alloy. Both alloys exhibited weak texture strength with predominantly large angle grain boundaries. The true stress-strain curve of the 1.5Zn alloy distinctly revealed dynamic recrystallization features. Notably, the 1.5Zn alloy exhibited higher peak stress and thermal activation energy compared to the 0Zn alloy. Furthermore, the 1.5Zn alloy demonstrated a lower critical strain for dynamic recrystallization, suggesting a heightened likelihood and increased degree of recrystallization. After hot deformation, the Mg-8Gd-3Y-xZn-0.6Zr alloy experienced a notable reduction in grain size, particularly evident in the 1.5Zn alloy, where the grains were smaller compared to the 0Zn alloy. Moreover, the texture strength of 1.5Zn alloy was obviously weaker than that of 0Zn alloy. Dynamic precipitation and dynamic recrystallization were more likely to occur at grain boundaries. Simultaneously, the constitutive model, hot processing map and recrystallization kinetics model were constructed for Mg-8Gd-3Y-xZn-0.6Zr alloy.