Evaluation of hardening and softening behaviors in Zn–21Al–2Cu alloy processed by equal channel angular pressing

Abstract

The microstructural evolution of as-cast and homogenized Zn–21Al–2Cu samples after two and six passes in an equal channel angular pressing (ECAP) at room temperature was reported. A homogenization treatment for 24 h at 350 °C was applied to the as-cast samples followed by deformation. An annealing heat treatment was performed on all samples after the ECAP process. Our results showed that the homogenized and deformed samples displayed a uniform fine-grained microstructure after annealing, while as-cast samples without homogenization treatment presented only some regions of fine-grained microstructure. The level of microsegregation was higher in the as-cast samples as compared to the homogenized ones even after annealing. Vickers microhardness measurement on samples after deformation is smaller than the original material indicating a softening. However, after the annealing treatment, the microhardness increased, indicating that there was a slight hardening of the material. Keywords: Severe plastic deformation, ECAP, Work softening, Annealing, Hardening, Fine grain