Manufacturing of Nano-Surface AA7075 Composites by Friction Stir Processing

Friction stir processing (FSP) is a novel processing technique that has been used for surface composite development and microstructural modification. The fabrication of Al₂O₃ nanoparticles (~40 nm) reinforced aluminum matrix composite (AMC) using FSP is studied in this paper with the aim of manufacturing high specific strength, hardness, wear and corrosion resistance surface nanocomposites for lightweight transportation applications. The Al₂O₃ nanoparticles were packed into the groove of 1 mm width and 7.5 mm depth that were machined in 15 mm thick plate of Aluminum alloy AA7075-O. Single pass FSP was performed using tool of cylindrical probe tool of 6 mm diameter and 20 mm diameter shoulder, constant rotation rate and traverse speed of 840 rpm and 40 mm/min respectively. A multipass FSP was performed to improve both dispersion and uniformity of the Al₂O₃ nanoparticles. The effect of post processing heat treatment after incorporating Al₂O₃ nanoparticles into different temper conditions of AA7075-T6 and AA7075-O was investigated. The fabricated AMC nanocomposites were analyzed and characterized using optical microscope, scanning electron microscope (SEM) and hardness testing. The hardness of the AMC increased with 89% higher versus that of the matrix alloy.