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

Abstract

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−1, respectively. The studied alloy was mainly composed of α-Mg, Mg3Zn6Y (I phase), Mg–Zn–Ce and Mg3Zn3Y2 (W phase). The constitutive equation of Mg alloy was obtained, and the apparent activation energy (Q) was determined as 200.44 kJ/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.