Microstructure and Mechanical Properties of Cast Hypereutectic Al-Si Alloy Nanocomposites

摘要

The effects of nanoparticles on the microstructure and mechanical properties of the as-castrnhypereutectic Al-20Si alloy were investigated. A small amount of SiC and Al_2O_3 nanoparticlesrnwere dispersed into Al-20Si alloy melts through an ultrasonic based dispersion method.rnMicrostructures were investigated using scanning and transmission electron microscopy as wellrnas optical microscopy. Mechanical properties of as-cast alloys were evaluated using tensilerntesting. The results showed that both the primary silicon as well as eutectic silicon wasrnsignificantly refined, resulting in marked enhancement of strength and especially ductility. ForrnAl-20Si-0.5 wt.% γ–Al_2O_3, the elongation is improved from 0.33% to 1.77% (increased by morernthan 400%). It is expected that the machinability of Al-20Si-0.5Al_2O_3 would also be muchrnimproved.