Evaluations of antimony and strontium interaction in an Al–Si–Cu–Zn die cast alloy

• Probable interactions between Sb and Sr in a complex Al–Si alloy were evaluated.
• Sequence of addition did not affect thermal and microscopical characteristics.
• Threshold ratio for the Sb and Sr interaction is proposed.

The interaction between antimony and strontium in an ADC12 die casting alloy is investigated comprehensively by using a computer aided cooling curve thermal analysis coupled with microstructure inspection. The results of the thermal analysis show significant changes in Al–Si eutectic reaction based on different concentrations of Sb and Sr. Sb reduces the efficiency of Sr in modifying the eutectic Si. Based upon the data obtained in this study, the threshold Sr/Sb ratio should exceed about 0.5 in order to obtain fully modified structure. Moreover, a pre-eutectic reaction of Al2Si2Sr intermetallic was detected for high concentrations of Sr.

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