Synergistic Effects of Cerium and Magnesium on Optimizing Electrical Conductivity and Mechanical Properties of AlSi3 Cast Alloys

To improve the strength and electrical conductivity (EC) of AlSi3 base alloys, the effect of Ce addition on the solidification, microstructure, and the mechanical and electrical properties of AlSi3 and AlSi3Mg0.5 is investigated. The results show that Ce addition increases the EC of the AlSi3Mg0.5 alloy by 1.3% International Annealed Copper Standard (IACS), owing to the reduction in Mg solutes in the Al matrix as confirmed by X‐ray analysis. Microstructural analyses have shown that incorporating 0.5 wt% Ce refines the eutectic Si structures in the AlSi3 alloy; this refinement effect is significantly enhanced in the presence of Mg. Specifically, the addition of Ce to the Mg‐containing (AlSi3Mg0.5) alloy induced a complete morphological transformation of the eutectic Si from plate‐shaped to entirely fibrous structures. Transmission electron microscopy analysis reveals nanosized precipitates composed of Ce and Mg within the eutectic Si. These precipitates are likely to inhibit the growth of Si particles, resulting in significant eutectic modifications. The incorporation of Ce into the AlSi3Mg0.5 alloy enhanced its yield strength, ultimate tensile strength, and elongation by 5, 11, and 59%, respectively. These improvements in the mechanical properties are primarily attributed to the solid solution strengthening effects of Mg and the modification of the eutectic structure.