In this work, the Al-10Si-2.5Cu-0.8Fe alloy was used as the base alloy to squeeze casting with different content Mg-10Al master alloy addition. The effects of microstructure and mechanical properties were investigated by XRD, OM, SEM, and tensile test analysis. The results show that with the increase of Mg addition, the morphology of eutectic Si in the alloy changes from strip to fiber and the size is obviously reduced. Al₈Mg₃FeSi₆ phase in the microstructure gradually grows, and the splitting effect on the matrix structure is increased. The tensile strength and elongation of the alloy increased first and then decreased with the increase of Mg content. When the Mg content is 1.38%, the tensile strength of the alloy reached a maximum of 289 MPa and the elongation is 2.24%. The hardness of the alloy gradually increases. When the Mg content is 2.51%, the hardness reaches 121.8 HV. The cleavage surface in the fracture becomes fine with the increase of Mg content, the number of dimples increases, and the fracture mode transitions from quasi-cleavage fracture to brittle fracture.

Lightweight aluminum alloy conductor materials (Al-Mg-Si alloys) require not only high electrical conductivity to reduce electrical loss, but also high strength to withstand extreme weather conditions. To improve electrical conductivity and mechanical properties of Al-Mg-Si alloy simultaneously, the rare earth La was introduced to modify the Al-Mg-Si alloy. The effect of La addition on the microstructure, tensile properties and electrical conductivity of cast Al-Mg-Si alloy was investigated systematically. Results indicate that the appropriate La content is helpful to improve the strength and electrical conductivity of Al-Mg-Si alloys. When the addition of La is 0.2wt.%, the α-Al grains are refined apparently, Mg and Si solute atoms in the Al matrix are reduced by the formation of Mg₂Si phase; the distribution of Al₁₁La₃ phases is uniform, and the morphology of AlFeSi phase transforms from continuous state to discontinuous state. The Al-Mg-Si-0.2La alloy exhibits the optimal tensile properties and electrical conductivity, with an ultimate tensile strength of 170 MPa, a yield strength of 88 MPa, an elongation of 18.9%, and an electrical conductivity of 44.0% IACS. These values represent improvements of 9.0%, 15.8%, 70.3%, and 17.3%, respectively, compared to the Al-Mg-Si alloy without La addition. However, excessive La deteriorates the properties of Al-Mg-Si-xLa alloys.