Effect of Al₂O₃ particle volume fraction on the microstructure and mechanical properties of aluminum matrix composites prepared by friction stir processing

The work involved the fabrication of Al₂O₃ particle-size AA2024-T6 aluminum-matrix composites via friction stir processing (FSP). It investigated how varying the volume fraction of Al₂O₃ particles affected the microstructure, mechanical properties, and impact toughness of the composites. Al₂O₃ particles increased the degree of grain refinement. They promoted increases in ultimate tensile strength (UTS), hardness, and impact toughness, which can be attributed to grain-boundary strengthening and Orowan looping. This work demonstrates stable particle dispersion at 10 vol.% Al₂O₃, exceeding the previously reported reinforcement threshold, while achieving uniform microstructures. The optimized FSP was performed using a dual-pin tool to ensure even distribution and prevent clustering in the stir zone. A significant correlation was observed between reinforcement volume and dynamic recrystallization behavior, as well as the resulting mechanical properties, indicating a practical approach to producing lightweight, high-impact-abrasion-resistant aluminum-matrix composites for the aerospace and defense industries. It is suggested that an even distribution increases impact resistance through efficient energy absorption, crack deflection, and slowed crack propagation.