Effect of ECAP temperature on formation of triple heterogeneous microstructure and mechanical properties of Zn–1Cu alloy

Abstract In this study, we systematically investigated the effect of equal channel angular pressing (ECAP) on the formation of heterogeneous microstructure and mechanical properties of Zn–1Cu alloy. The obtained results showed that both low-temperature (room temperature and 150 °C) and high-temperature (200 and 300 °C) ECAP processing with eight passes facilitate the generation of triple heterogeneous microstructure, including heterogeneous distribution of CuZn4 precipitates, η-Zn grain size, and η-Zn grain texture in the precipitates-free zones (PFZs) and precipitates zones (PZs). The major microstructural difference is that the PZs in low-temperature ECAP alloys are composed of DRX grains with weak texture, while that in high-temperature processed alloys consist of DRX grains with even stronger texture intensity than the PFZs. As both PFZs and PZs act as the soft domains, the ECAP alloy processed at low temperatures show low strength but high ductility with elongation higher than 60%. The hetero-deformation induced strengthening could be effectively activated in high-temperature processed alloys because the PZs become much stronger, which contributes to the excellent mechanical properties with high ultimate tensile strength of 231 MPa and moderate elongation of 25.9%. This work provides a unique insight into the design and preparation of Zn–Cu based alloys with tunable strength and ductility.