Preliminary Results on the Effects of Modification during Semi-Solid Processing of Al-7%Si Alloys

Abstract

Silicon is one of the most important alloying elements incorporated in Al-alloys. Its addition is to improve castability, fluidity, reduce shrinkage and renders superior mechanical properties. The morphology of silicon however plays an important role on the properties of finished products. Therefore, the usual practice is to modify the as-cast flake or acicular silicon morphology employing special heat treatment or addition of certain modifiers. As a result, the silicon morphology changes to fibrous form with enhanced mechanical properties of the as-cast parts. For conventional casting, this treatment has been investigated widely by so many researchers but in the SSM processing, few published papers could be found. In this article, the addition of Sr as a modifier for Al-Si binary alloy is investigated for semi-solid alloy using the patented SEED process, "Swirled Enthalpy Equilibration Device".