Phase transformation and property improvement of Al–0.6Mg–0.5Si alloys by addition of rare-earth Y

Abstract Al–0.6Mg–0.5Si (wt%) alloys with varying Y contents are prepared, and effects of Y on the microstructure, electrical conductivity, and mechanical properties are investigated. The results show that Al–0.6Mg–0.5Si alloys are refined by addition of Y, and the average grain size is refined from 254 to 168 μm with the addition of Y content from 0 to 0.4 wt%. Addition of Y can lead to the formation of the AlSiY phase and AlFeSiMgY mixed phase as Y can react with elements such as Fe and Si in the alloy. The electrical conductivity of Al–0.6Mg–0.5Si alloys initially increases and subsequently decreases with increasing Y content. The electrical conductivity reaches its highest value of 54.3% IACS by addition of 0.3 wt% Y, which is improved by 4% compared with that without addition of Y. The tensile strength increases with increasing Y content, and the highest value is 154 MPa by addition of Y with 0.4 wt%, which is improved by 12.4%. Elongation of alloys initially increases and subsequently decreases with increasing Y content. The strength improvement of Al–0.6Mg–0.5Si alloys is mainly attributed to grain refinement and precipitation of granular and short rod-like secondary phases caused by the addition of Y into Al–0.6Mg–0.5Si alloys.