Influence of aging and varying weight fraction of Al₂O₃ particles on the mechanical behaviour and volumetric wear rate of Al 7075 alloy composite produced by liquid metallurgy route

The effect of heat treatment, particle size, varying weight% (2, 4, 6 and 8%) of Al₂O₃ particles on the mechanical and wear behaviour of Al 7075 alloy composite is investigated. Two sets of Al 7075 alloy composite samples reinforced separately with as-received (45 μm) Al₂O₃ particles and nano-sized (40–50 nm) Al₂O₃ particles were produced by stir casting route. The stir cast samples were initially solutionized and then artificially aged at 120 °C for durations of 3, 12, 24, 48, 60, 72, 84 and 96 h. The hardness, tensile, compression and pin on disc wear tests were carried out on the aged and non-aged samples. The mechanical test results showed an enhancement of the composites' mechanical properties due to the effect of artificial aging and as well as the addition of varying wt% of (coarse or nano-sized) Al₂O₃ reinforcement. The T6-aged Al 7075 alloy composite specimens reinforced with nano-Al₂O₃ particles exhibited enhanced hardness, tensile and compression strength compared to the T6 aged and non-aged samples reinforced with coarse alumina reinforcement. An increasing trend was observed due to the addition of upto 6 wt% of Al₂O₃ reinforcement, beyond which the samples exhibited a decline in its tensile and compression strength. The tensile fracture surface of the samples was characterized by FESEM to determine the deformation mechanism. Pin on disc wear tests under varying load conditions revealed that the T6-aged composite samples showed higher wear resistance than the unreinforced Al 7075 alloy. Nonetheless, the T6-aged nano-Al₂O₃ reinforced samples showed superior resistance to wear loss compared to its coarse Al₂O₃ reinforced counterpart. The worn surface of the samples was characterized by FESEM to examine the mechanism of wear. The test samples were also characterized using XRD and EDS analysis. (paper)