Effect of Al2O3 Particles on Mechanical and Wear Properties of 6061al Alloy Metal Matrix Composites

Particulate reinforced aluminium matrix composites are being considered for their superior mechanical and tribological properties over the conventional aluminium alloys, and therefore, these composites have gained extensive applications in automotive and aerospace industries. In this investigation, the fabrication of 6061Al composites with different weight percentage of Al2O3 particles up to 0-9% was processed by liquid metallurgy route. For each composite, reinforcement particles were preheated to a temperature of 200°C and then dispersed in steps of three into the vortex of molten 6061Al alloy rather than introducing all at once, there by trying to improve wettability and distribution. Microstructural characterization was carried out for the above prepared composites by taking specimens from central portion of the casting. Microstructural characterization of the composites has revealed fairly uniform distribution of Al2O3 particulates. XRD analysis revealed the presence of Al2O3 and other phases. The tensile strength and hardness of the resultant composites were examined. It was revealed that the 6061Al- Al2O3 composites have a higher tensile strength than 6061 aluminium alloy with reduced ductility. It was found that an increase in the Al2O3 content in 6061Al alloy contributed in enhancing the hardness of the composites. The wear test was conducted using computerized pin on disc wear tester with counter surface as EN31 steel disc (HRC60) and the composite pin as specimens, demonstrated the superior wear resistance property of the composites.