Tailoring the strength and corrosion resistance of Al-7Si: Eutectic Si modification by Sr and Sc

The effects of different content of Sr and Sc on the microstructure, mechanical properties and corrosion resistance of an Al-7Si alloy were investigated. The presence of Sc in the Sr-modified Al-Si alloy resulted in multiple types of eutectic Si morphologies. The modification of eutectic Si improved the yield strengthen and elongation of Al-7Si alloys, but lead to the increase of boundaries between α-Al and eutectic Si particles, which caused decrease of corrosion resistance and polarization resistance. The incomplete modification offered a possibility to satisfy the require that a compromise between mechanical properties and corrosion resistance. The relationship between the content of Sr and Sc and the morphologies of eutectic Si in the alloy was also summarized.