The effects of strontium addition on the microstructures and mechanical properties of al-7si alloy reinforced with in situ al3Ti Particulates

Abstract

Al3Ti particulates (5 vol%) were produced in situ via aluminum-K2TiF6 reactions in an Al-7Si alloy. The effects of strontium (Sr) addition (200 ppm) on the microstructure and mechanical properties were studied. In addition to the modification on the morphology of eutectic Si, Sr addition resulted in the reduction of Al3Ti particulate sizes. As a result, the yield strength, tensile strength and ductility of composites with Sr addition are simultaneous improved compared to composites without Sr addition for both as-cast and T6 states. The enhanced mechanical properties are attributed to the small-sized Al3Ti particulates and a refined microstructure.