Hot Deformation Behavior and Microstructure Evolution of a Novel High-Zn Containing Al-Zn-Mg-Cu-Zr Alloy

The hot deformation behavior of a novel high-Zn containing Al-Zn-Mg-Cu-Zr alloy was investigated by isothermal compression tests under the conditions of 350-500 degrees C and 0.0001-10 s-1. Arrhenius constitutive model and diffusion model were established to describe the flow behavior. Meanwhile, the microstructure evolution and the effect of the Zener-Hollomon parameter on dynamic recrystallization (DRX) behavior was investigated. The results show that both the Arrhenius model and diffusion model describe the flow behaviors well and the Arrhenius model shows better prediction ability. Microstructure characterization indicates that dynamic recovery (DRV) is the main dynamic softening mechanism during the entire hot deformation process, and the DRX mechanism varies at different deformation conditions. Discontinuous dynamic recrystallization and continuous dynamic recrystallization are the main DRX mechanisms under the deformation condition with moderate and low ln Z values, respectively. Moreover, at an extremely low strain rate (0.0001 s-1), the enhancement of DRV and particle pinning effect diminish the driving force for DRX at elevated temperature, resulting in a slight decrease in the proportion of DRX grain.