Enhancing significantly the strength and tribological response of Al7075 alloy using nano-ZrO2 reinforcement

Ball milling is an effective method for developing a homogenous and refined microstructure for composites. In this study, we synthesized ultrahigh strength Al7075/xZrO2 alloy nanocomposites. These nanocomposites were specially fabricated by the in-situ powder metallurgy technique from high-purity elemental powders through a multi-step process, which included ball milling, uniaxial cold compaction, traditional sintering in an inert atmosphere, and hot extrusion. The ZrO2 nanoparticles with varying volume percentages (x vol.% = 0, 1.25, 2.53, 3.84, and 5.19) were used as a reinforcement. Ball milling was performed to mechanically alloy the elemental powders that reduce the grain size of the powder and homogeneously disperse the nano ZrO2 in the matrix. The physical, mechanical, microstructural, and tribological properties of the nanocomposites were determined. The results showed that adding 2.53 vol.% ZrO2 nanoparticles considerably improved the mechanical and tribological properties. The tensile strength and yield strength of the 2.53 vol.% alloy nanocomposites increased significantly. The wear resistance of the nanocomposite increased up to 5.19 vol.% ZrO2. The results obtained from the newly developed composites were compared with those of Al7075 alloy composites produced earlier.