The influence of rare earth element lanthanum on the microstructures and properties of as-cast 8176 (Al-0.5Fe) aluminum alloy

The effects of rare earth element on the microstructures, tensile properties and electrical properties of aluminum alloys have brought about widespread interesting in the last few decades. However, contradictory results are usually reported, and there is little research concerning the effect law of trace lanthanum (the addition is below 0.1 wt%) on the as-cast microstructures, electrical conductivity and the tensile properties of 8176 aluminum alloy which is one of the most widely used aluminum conductor alloy. In this work, solidification experiments were performed with 8176 aluminum alloy and the effects of lanthanum addition was investigated. The results demonstrated that the lanthanum addition can promote the refinement of the alpha Al grains, the modification of Al13Fe4 intermetallic phase. The elongation and electrical conductivity simultaneously enhance with lanthanum addition when the additive amount is less than 0.08%, while the elongation decreases when the additive amount reaches to 0.1% due to the formation of intermetallic phase. The enhancement of the elongation is mainly ascribed to the modification of Al13Fe4 intermetallic phase, the enhancement of the electrical conductivity is attributed to the reduction of solid solubility of Si and Fe elements in Al matrix. These results indicate that the addition of micro-alloying element lanthanum is a prospective method for simultaneously elevating the electrical conductivity and tensile properties of the 8176 aluminum alloy.