Enhanced strength-ductility synergy in a rheo-diecasting semi-solid aluminum alloy

Common strengthening strategies for casting aluminum alloys sacrifice ductility. Herein, the strength-ductility synergy of a rheo-diecasting semi-solid Al–Si–Mg–Cu–Fe–Sr alloy was tailored by optimizing the pouring temperature and subsequent heat treatment. The results demonstrated that with decreasing pouring temperature from 700 °C to 670 °C, the average grain diameter of primary α-Al grains and porosity decreased, while the average shape factor and solid phase fraction increased, resulting in improved mechanical properties of the alloy. After T6 heat treatment, changes in the morphologies of eutectic Si phases and Al3Fe phases were observed, and Mg2Si precipitates were formed, which further enhanced the mechanical properties of the alloy.