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.