Microstructural study and differential scanning alorimetry analysis at elevated temperatures of uperheated as-cast A357 alloy

Abstract

The microstructure of superheated as-cast A357 alloy has been analysed to study the solidification structures of α-Al dendrites, eutectic Si particles and intermetallic compounds at different sections of the specimen. The primary dendritic arms are broken to globular and spherical shaped of α-Al dendrites due to the thermal effect of superheating thermal treatment. Differential scanning calorimetry showed faster formation of endothermic peaks of superheated as-cast A357 alloy relatively also believed to be attributed by superheating thermal treatment. The solidification sequence of superheated A357 alloy was same as Sr modified Al7Si-Mg alloy [4] except for the reaction involving Al5FeSi intermetallic compound which started with Liq. → Al dendrites followed by Liq. → Al + Si and lastly Liq. → Al + Si + Mg2Si + Al8FeMg3Si6.