Effect of Zener–Hollomon Parameter on High-Temperature Deformation Behaviors of Mg–6Zn–1.5Y–0.5Ce–0.4Zr Alloy

High-temperature compressive deformation behaviors of Mg–6Zn–1.5Y–0.5Ce–0.4Zr alloy were investigated at temperatures and strain rates ranging from 523 to 673 K and from 0.001 to 1 s,respectively.The studied alloy was mainly composed ofα-Mg,MgZnY (I phase),Mg–Zn–Ce and MgZnY(W phase).The constitutive equation of Mg alloy was obtained,and the apparent activation energy (Q) was determined as 200.44 k J/mol,indicating that rare earth phase increases the difficulty of deformation.The work hardening involves three stages:(1) linear hardening stage;(2) strain hardening stage;and (3)softening and steady-state stage.During these three stages,the dislocation aggregation and tangling,dynamic recovery and recrystallization occur sequentially.To characterize the dynamic recrystallization (DRX) volume fraction,the DRX kinetics was investigated using the Avrami-type equation.The deformation mechanism of magnesium alloy under different Zener–Hollomon parameter (Z) value conditions was also studied.At high Z values and intermediate conditions,dislocations rapidly generate and pile up in the alloy.Recrystallization is hardly seen at this time.At low Z condition,the DRX occurs in the alloy.