Effect of Trace Elements La, Ti and Homogenization on Electrical Properties of Pure Aluminum

Al-La, Al-Ti and Al-La-Ti alloys were prepared to study the effects of Ti and La on the electrical conductivity and strength of alloys. The electrical conductivity, strength and microstructure evolution of alloys before and after homogenization treatment at 500 °C for 8 h were investigated. The results show that when the content of La does not exceed 0.3 wt%, the electrical conductivity of Al-La can keep a high level as 60.35% IACS due to the precipitation of the compounds containing La, Si and Fe. The strength of Al-Ti alloy is rapidly enhanced with the increase of Ti due to the increasing content of Ti atoms in the α-Al solution. When La and Ti are added simultaneously, the strength of alloys is higher than that of Al-La alloys, and the electrical conductivity is decreased compared with that of Al-La alloys but is higher than that of the Al-Ti alloy, which is mainly attributed to the formation of the new secondary phase Ti₂Al₂₀La. Homogenization treatment has little effect on the microstructure of alloys but reduces the number of casting defects, thereby increasing the electrical conductivity of all samples.