Mechanical and Wear Properties of Graphite Reinforced Aluminum Metal Matrix Composites Processed by Ultrasonic-Stir-Squeeze Casting.

In the present study, the researchers have utilized graphite as the reinforced phase of the aluminum metal matrix nanocomposites (AMMNCs) owing to its high strength and lubricating properties. The AMMNCs are processed through combined ultrasonic-stir-squeeze casting process to ensure homogeneity of the reinforced phase in the matrix while minimizing the porosity of the cast ingot. The phase and microstructure of the developed AMMNCs are investigated through characterization techniques such as x-ray diffraction and Field Emission Scanning Electron Microscopy. AMMNCs exhibit lower density in comparison with the as-cast aluminum alloy (AA2014). Hardness of the composites have improved due to addition of the reinforcement, but adversely the porosity also increases with the increase in concentration of graphite. The tribological properties of the AMMNCs are investigated under dry condition and compared with that of the as-cast AA2014. Addition of graphite improves the wear properties of the AMMNCs. However, parameters like concentration of graphite and applied load affect the wear rate considerably. Post-tribological characterization of the wear scars provide detailed information on the influence of hardness and elastic modulus on the tribological properties of the AMMNCs. [ABSTRACT FROM AUTHOR]