Microstructure, mechanical properties and fracture behavior of 6061 aluminium alloy-based nanocomposite castings fabricated by ultrasonic processing

It has been revealed that microstructure and mechanical properties of aluminium castings can be significantly improved by adding nanoparticles as reinforcement to fabricate aluminium-based metal matrix nanocomposites (MMNCs). One of the common problems in fabricating MMNCs is the agglomeration of reinforcement nanoparticles. In the present study, ultrasonic stirring technology (UST) is deployed to assist 6061 nanocomposite casting process by promoting the dispersion and deagglomeration. Al2O3/SiC nanoparticles are used as reinforcement materials. Nanoparticles are added into the molten alloy and dispersed by ultrasonic cavitation and acoustic streaming caused by UST. The microstructure, fracture behaviour and mechanical properties of 6061-based MMNC samples have been investigated. Tensile strength and yield strength of MMNC samples remain at the same level while the elongation increases significantly compared to reference samples.