Effect of Zinc Addition on the Microstructure and Properties of Al–Si–Cu–Mg Cast Alloy

The addition of zinc (Zn) to a hypoeutectic Al–Si–Cu–Mg alloy leads to an improvement in grain size. It also causes a transformation of the needle-like structure of the β-Fe phase into a Chinese character-like or short rod-like α-Fe phase. Concurrently, the addition of Zn also improves the solidification temperature range of the alloy and enhances the fluidity of the alloy. The alloy exhibits the most optimal microstructure and the narrowest solidification temperature range when 0.3 wt% of Zn is added. The results demonstrate that the alloy's fluidity is enhanced by 91.55% compared to the traditional unmodified Al–8Si–1Cu–0.35 Mg casting alloy. Furthermore, the addition of 0.3 wt% Zn resulted in a maximum value of 281.5 MPa for the mass index Q, indicating the optimal tensile properties.