Microstructure and mechanical properties of Al-Si eutectic alloy modified with Al-3P master alloy

The fraction of primary Si and primary α-Al in Al-Si eutectic alloy were largest after modification at 740 °C when a certain amount of Al-3P was added. The fraction of primary Si and primary α-Al in Al-Si eutectic alloy first increased and then decreased with increasing amount of Al-3P. The fraction of primary Si and primary α-Al in the Al-Si eutectic alloy was largest when the added amount of Al-3P modifier was 0.4wt.%. The fraction of primary Si and primary α-Al decreased with further increased Al-3P modifier. The size of the primary Si decreased continuously. Compared to the unmodified Al-Si eutectic alloy, the tensile strength and elongation of the alloy modified with 0.4wt.% Al-3P at 740 °C increased by 7% and 74%, respectively.