Microstructure and mechanical properties of Zr‐modified Al–7Si–0.35Mg–0.2Ti cast alloy.

In this research, four specimens of hypo‐eutectic Al–7Si–0.35Mg–0.2Ti–xZr (x = 0, 0.1, 0.2, 0.3 wt%) cast alloys were fabricated via a traditional casting method. The effect of different concentrations of Zr on the microstructure and mechanical properties of cast alloys was investigated through metallographic observation, SEM analysis, TEM observations, tensile strength testing, and Vickers hardness test. The results show that the plate‐like shape eutectic Si phase is gradually transformed into fine fibrous eutectic Si phase, and is more evenly distributed as the content of Zr increased. The α‐Al matrix grains are transformed from dendrites to isometric grains, of which the grains sizes became smaller. The results of the tensile test show that with the addition of 0.2% Zr, Al–7Si–0.35Mg–0.2Ti alloys obtain the best tensile properties. The ultimate tensile strength and elongation values are 221 MPa and 11%, the number of which is increased by 14.5 and 71.9% than base alloy, respectively. Additionally, the alloy's yield strength, Vickers hardness, and other comprehensive mechanical properties have also improved significantly. [ABSTRACT FROM AUTHOR]