Reduction in secondary dendrite arm spacing in cast eutectic Al–Si piston alloys by cerium addition

The effects of Ce on the secondary dendrite arm spacing（SDAS） and mechanical behavior of Al–Si–Cu–Mg alloys were investigated. The reduction of SDAS at different Ce concentrations was evaluated in a directional solidification experiment via computer-aided cooling curve thermal analysis（CA-CCTA）. The results showed that 0.1wt%–1.0wt% Ce addition resulted in a rapid solidification time, ?ts, and low solidification temperature, ?TS, whereas 0.1wt% Ce resulted in a fast solidification time, Δta–Al, of the α-Al phase. Furthermore, Ce addition refined the SDAS, which was reduced to approximately 36%. The mechanical properties of the alloys with and without Ce were investigated using tensile and hardness tests. The quality index（Q） and ultimate tensile strength of（UTS） Al–Si–Cu–Mg alloys significantly improved with the addition of 0.1wt% Ce. Moreover, the base alloy hardness was improved with increasing Ce concentration.