Effect of Iron-Rich Intermetallic and Eutectic Si Accumulation on Al-Si-Mg Alloy

Abstract

Al-Si-Mg alloys, an important aluminum cast alloys, are excessively used inmanufacturing of critical components due to their high strength to weight ratio, flexibility ofmanufacturing designs, economic processing and capital material cost for automotive industry. Thisresearch is aimed to study microstructure evolution including distribution and morphology ofiron-rich intermetallic, as well as eutectic Si accumulation and their effect on mechanical propertiesof Al-Si-Mg (A356) casting alloy after artificial ageing. The results show that formation of iron-richintermetallic and eutectic Si accumulation resulted in surprisingly opposite mechanical properties,especially ductility. The elongations deceased with increase of area of accumulated eutectic Si and theamount of needle-like iron-rich intermetallic. When the area of accumulated eutectic Si reached 31%of the microstructure of the A356 alloy, the strength and elongation were respectively damaged to129.69 MPa and 1.05%. Moreover, the amount of needle-like iron-rich intermetallic increased, thestrength and elongation respectively decreased.