Microstructural characterisation and mechanical performance of AA6063 hybrid aluminium matrix nanocomposites reinforced with Al2O3 and SiC nanoparticles

The present study examines the microstructural features and mechanical properties of hybrid nanocomposites of the AA6063 aluminium matrix incorporating Al 2 O 3 and SiC nanoparticles. Three reinforcement weight percentages (2, 4, and 6 wt.%) were used to produce the composites via ultrasonic-assisted stir casting, and the composites were T6 heat-treated to improve their properties. The uniform dispersion of the reinforcement particles was confirmed by microstructural analysis using SEM, EDS, and XRD at lower reinforcement levels, while agglomeration was observed at higher reinforcement levels. The XRD results confirmed the formation of strengthening Mg 2 Si phases and the presence of Al 2 O 3 and SiC, without any harmful interfacial compounds. Mechanical evaluation showed a significant improvement in properties as reinforcement content increased. Hardness increased by 59%, and ultimate tensile strength increased by 38% over the base alloy. However, ductility was reduced by approximately 55% due to the brittle nature of ceramic reinforcements and increased stress concentrations. The 4 wt.% reinforced composite was found to be the most effective in terms of strength and integrity. Among the compositions studied, the 4 wt.% hybrid nanocomposite provided the most effective combination of strength and ductility. However, the 6 wt.% composite achieved the highest strength values but at a measurable cost to elongation. This is attributed to reinforcement particle clustering at the higher loading. The results were compared with the available literature and indicate that the hybrid composites performed well, outperforming single-reinforced composites, a result attributed to their strengthening mechanism. The study demonstrates the benefits of hybrid nanoparticle reinforcement and T6 heat treatment in improving the performance of aluminium matrix composites for structural applications.