Mechanical, microstructural, and tribological response of pure-Al reinforced with Al2O3 composites developed through powder metallurgy route

Despite the extensive use of aluminum matrix composites, systematic studies on the influence of Al 2 O 3 reinforcement content on the microstructural evolution, Rockwell hardness (HRB), densification, and erosion-wear behavior of pure aluminum composites fabricated via powder metallurgy remain limited. Therefore, the present study aims to investigate the effects of adding Al 2 O 3 microparticles on the microstructural, mechanical, and tribological performance of pure Al-based composites. Al–Al 2 O 3 composites containing 0, 1, 2, and 3 wt% Al 2 O 3 , synthesized via the sol–gel method, was successfully fabricated through the powder metallurgy route. Microstructural analysis revealed progressive grain refinement as reinforcement content increased, with a uniform particle distribution observed up to 2 wt% Al 2 O 3 , whereas slight agglomeration occurred at 3 wt%. Rockwell hardness improved markedly from ∼81.7 HRB to ∼105.8 HRB due to grain refinement, particle strengthening, and restriction of localized plastic deformation. Density measurements indicated improved densification with increasing reinforcement content, although the experimental densities remained slightly lower than the theoretical values due to residual porosity. Erosion wear behavior was strongly influenced by impingement angle and particle velocity. Pure Al exhibited maximum erosion at lower impingement angles, characteristic of ductile erosion behavior, while the reinforced composites showed superior erosion resistance. Under the investigated erosion conditions, the 2 wt% Al₂O₃ composite exhibited the highest erosion resistance, with a maximum erosion-rate reduction of approximately 66% relative to pure Al at an impingement angle of 45°. However, a further increase in reinforcement content to 3 wt% led to particle agglomeration and weakened interfaces, resulting in reduced erosion resistance under severe impact conditions.