Effect of heat treatment on the mechanical properties of the aluminium alloys AA2024 with nanoparticles

Abstract

An aluminum alloy, AA2024, was reinforced with different mass fractions of titanium dioxide nanoparticles (0%, 2.5%, 5% and 7.5%) by stir casting, this was followed by a solution treatment at 500°C for 3 h, quenching in water, and aging at 175°C for 3 h. The purpose was to investigate the effect of TiO 2 nanoparticles on the microstructure and mechanical properties of the stir-cast aluminium alloy AA2024. Through ageing treatment, the effects of heat treatment conditions on the homogeneity of the impact toughness and microhardness of AA2024 with nanoparticles were studied. After heat treatment and ageing treatment, the hardness values and impact resistance in different positions of the composite aluminium are greatly improved compared to the unreviewed samples. Furthermore, the distribution of elements existed in the interior of the grain boundary, and the grain was homogeneous after heat treatment, which increased the intercrystallite hardness values. The results showed that 5 wt.% TiO 2 was the optimum fraction to achieve the highest microhardness and impact resistance. Using the optimum content of TiO 2 and heat treatment, the microhardness and impact resistance were significantly improved over the unreinforced aluminium matrix, specifically due to an increased number of fine precipitates that were uniformly distributed after the heat treatment.