Modification Effects of Lan-Rich Mischmetal on Hypereutectic Al-24% Si Alloy

The influences of RE on the microstructure and mechanical properties of hypereutectic A1-24%Si alloy were investigated.Microstructure was examined by SEM.The results show that the addition of La has strong modification effect on the microstructure of hypereutectic Al-24%Si alloy.The average grain size of primary Si phase can be reduced to 40μm,meanwhile,its modification effect on the eutectic silicon is more obvious,and the eutectic silicons can be transformed into the fine lamella ones.The mechanical properties are improved.The modification mechanism was also discussed.