Tribological behavior of pure Mg and AZ31 magnesium alloy strengthened by Al2O3 nano-particles

This paper investigates the wear and friction behavior of pure Mg and AZ31 Mg alloy and their composites reinforced with 2 wt.% Al2O3 nano-particles. Wear tests were conducted on as-cast materials using a pin-on-disc configuration under normal stresses of 0.5, 1.0 and 1.5 MPa at sliding speeds of 0.5 and 1.5 m/s for sliding distances up to 2000 m. Sub-surface micro-hardness profiles and hot compression flow curves, measured at temperatures similar to that of the contact surface, were used to investigate the work-hardening behavior of the materials. The lower wear resistance of the monolithic pure Mg and AZ31 magnesium alloy is explained by the work softening due to contact temperature rise. Composite materials, however, showed much lower wear rates mainly due to the strength improvements caused by nano-particles. Although grain refinement, higher load-bearing capacity, and improved hardness have some contributions to the overall wear resistance, increased work-hardening capacity due to the interaction of dislocations and nano-particles can be considered as the main mechanism improving wear behavior of the present nano-composites.