Evaluation of the Hardening and Softening Effects in Zn-21Al-2Cu with as Cast and Homogenized Microstructure Processed by Equal Channel Angular Pressing

摘要

In this work it is reported the evolution of the microstructure of the as-cast and homogenized Zn-21Al-2Cu samples, after 2 and 6 passes in an equal channel angular pressing (ECAP) at room temperature. A homogenization treatment for 24 h at 350 ℃ was applied in the as-cast samples and then they were deformed. An annealing heat treatment was made in all samples after ECAP process. One of the main results is that the homogenized and deformed samples showed a uniform fine-grained microstructure after annealing, while as-cast samples without annealing presented only some regions with fine-grained microstructure. The micro segregation level was higher in the as-cast samples in contrast 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.