Microstructure and mechanical property developments in Al-12Si gravity die castings after Ti and/or Sr additions

This study evaluates the influence that modification and refinement have on the mechanical properties of the eutectic Al-Si alloy and on the quantitative and qualitative correlations with the microstructure. A general improvement in the mechanical properties of the alloys was observed after the additions. The best mechanical values were obtained when both Ti and Sr were present, in particular for the experimental composition with the higher Ti/Sr ratio. The results also indicate the development of a ductility trough for the alloy with lower Ti/Sr ratio, indicating a poisoning effect of Ti over Sr.