Mechanical and Wear Properties of Aluminum-Based Nanocomposites Fabricated through Ultrasonic Assisted Stir Casting

Abstract

Abstract The aluminum alloy AA6061 with 0.004, 0.008, 0.012, and 0.016 volume fractions of silicon carbide (SiCp) nanocomposites were fabricated using a semi-solid stirring assisted ultrasonic cavitation technique. Specimens are tested for morphology, density, mechanical, and wear properties. The density, strength, and microhardness of the nanocomposites increased with the increase of SiCp nano-reinforcement particles in the matrix. The yield strength of the SiCp-reinforced nanocomposites was evaluated by considering various strengthening mechanisms. It is found that the yield strength of the nanocomposites increased by 96 % for 0.004, 172 % for 0.008, 158 % for 0.012, and 206 % for 0.016 volume fractions of SiCp compared to the base alloy. The dislocation mismatch effect and Orowan strengthening effect are found to play a significant role in the SiCp-reinforced AA6061 nanocomposites. The dislocation mismatch effect increased with the reinforcement particles’ size reduction in the matrix. The Orowan strengthening effect increased up to 1.56 nm critical size of SiCp, and above that it decreased slightly. The experimental results are compared to predicted results obtained from various analytical models. The experimental results are observed to be in close agreement with the Mirza and Chen model. The wear loss of nanocomposites decreased with an increase in the nano-sized SiCp reinforcement quantity in the matrix. The amount of 0.004, 0.008, 0.012, and 0.016 volume fractions of nano-sized SiCp reinforcement additions to the AA6061 alloy matrix decreases the wear coefficient by 19.23 %, 38.46 %, 57.69 %, and 62.69 %, respectively. The worn surfaces were also analyzed using a scanning electron microscope and energy-dispersive X-rays.