The effects of Mg2Si(p)on microstructure and mechanical properties of AA332 composite

Abstract

This paper describes a study on the effects of <TEX>$Mg_2Si_{(p)}$</TEX> addition on the microstructure, porosity, and mechanical properties namely hardness and tensile properties of AA332 composite. Each composite respectively contains 5, 10, 15, and 20 wt% reinforcement particles developed by a stir-casting. The molten composite was stirred at 600 rpm and melted at <TEX>$900^{\circ}C{\pm}5^{\circ}C$</TEX>. The <TEX>$Mg_2Si$</TEX> particles were wrapped in an aluminum foil to keep them from burning when melting. The findings revealed that the microstructure of <TEX>$Mg_2Si_{(p)}/AA332$</TEX> consists of <TEX>${\alpha}$</TEX>-Al, binary eutectic (<TEX>$Al+Mg_2Si$</TEX>), <TEX>$Mg_2Si$</TEX> particles, and intermetallic compound. The intermetallic compound was identified as Fe-rich and Cu-rich, formed as polygonal or blocky, Chinese script, needle-like, and polyhendrons or "skeleton like". The porosity of <TEX>$Mg_2Si_{(p)}/AA332$</TEX> composite increased from 8-10% and the density decreased from 9-12% from as-cast. Mechanical properties such as hardness increased for over 42% from as-cast and the highest UTS, elongation, and maximum Q.I were achieved in the sample of 10% <TEX>$Mg_2Si$</TEX>. The study concludes that combined with AA332, the amount of 10 wt% of<TEX>$Mg_2Si$</TEX> is a suitable reinforcement quantity with the combination ofAA332.