Effect of graphene addition on the mechanical and tribological behavior of nanostructured AA2124 self-lubricating metal matrix composite

In the current research, the mechanical and tribological behavior, and structural evolution of AA2124-3 and 5-wt.% graphene (G) composites prepared by a combination of ball milling and hot extrusion were investigated. Properties such as macro and micro-hardness, nanohardness, tensile and lattice strain were characterized. Wear rates, coefficient of friction (COF) as well as nanoscratch testing were used to investigate the self-lubricating tribological behavior. X-ray diffraction, optical and scanning electron microscopy were employed. Hardness of the AA2124-G composite increased by 133 and 102%, the wear rates decreased by 34 and 25%, and the COF decreased by 25 and 9%, for the 3 and 5 wt.% G composites, respectively compared to the plain alloy extrudates. The AA2124-3 wt.% G composite displayed the least scratch depth and width and highest nanohardness. The uniform distribution of the 3-wt.% G-particles within the Al-matrices formed uniform G-tribofilm, which enhanced the tribological behavior of the composite.