Evolution of grain size and texture of Zn-0.5Cu ECAP alloy during annealing at 200 ℃ and its impact on mechanical properties

Abstract

Due to the low recrystallization temperature, the microstructure of wrought Zn alloys is naturally unstable, which affects their mechanical properties and limits their application. Therefore, it is crucial to elucidate the effect of microstructural evolution on mechanical properties of wrought Zn alloys. In this work, annealing treatment was performed on a Zn-0.5Cu (wt%) equal channel angular pressure (ECAP) alloy at 200 °C for different durations to investigate the microstructure evolution and its effect on the mechanical properties. An abnormal phenomenon that strength and ductility of the ECAP alloy decrease monotonically with increasing annealing time was observed, which is remarkably different from most other metallic alloys (Mg, Al, Cu, etc.). Detailed microstructure observations were conducted to unveil the mechanisms behind this abnormal phenomenon. Annealing for 1440 min induced not only an abnormal increase in texture intensity from 17.06 to 30.53 (which can be ascribed to preferential growth of high-texture grains with the<−12 to 10 >and<01–10 >components) but also a significant grain growth from 3.3 µm to 32.7 µm. Grain growth and dislocation annihilation resulted in the loss of strength, while the abnormal decrease in ductility during annealing was primarily due to texture enhancement and grain coarsening. The present work could provide guidance for the production and application of wrought Zn alloys in biomedical fields.