Experimental and Numerical Investigations of the Fatigue Life of AA2024 Aluminium Alloy-Based Nanocomposite Reinforced by TiO2 Nanoparticles Under the Effect of Heat Treatment

Abstract

Using aluminium metal matrix nanocomposites has recently gained increased attention in the industry due to their high strength and ductility. In this paper, TiO2 nanoparticles in volume percentages of 5 wt. % were added to the AA2024 alloy using the stir casting method. Using a novel powder injection system, TiO2 nanoparticles with an average particle size of 30 ± 5 nm was added to the matrix. The influence of TiO2 content on the fatigue life before and after heat treatment was studied. The results showed the fatigue properties of AA2024 with TiO2 nanoparticles increased after heat treatment. The optimum improvement in fatigue properties was obtained at 5 wt. % TiO2 after heat treatment, with an improving fatigue life in 14.71% compared with sample based. This is due to an increased number of fine precipitates besides its uniformly distributed after heat treatment. The fatigue life of the composite materials with added nanoparticles was investigated using a finite element-based ANSYS workbench. There was a good match between what happened in the experiments and what happened to the numerical fatigue strength. For the composite materials, the difference between the experimental and numerical values of fatigue strength was not greater than 4% for the matrix. The results also, indicated that, after ageing, the precipitate-free zone at the inter-dendritic zone disappeared or became smaller. However, after adding 5 wt. % of titanium and, also, performing heat treatment, it is not possible to precipitate the Al2CuMg precipitates, and, instead of it, the Al3TiCu and Al7TiCu phases precipitates have been formed.