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The present study explores the effect of nano-ZrO2 particles reinforcement on the microstructural refinement, mechanical strengthening, and tribological enhancement of AZ31 magnesium alloy composites synthesised via ultrasonic-assisted stir casting. The composites with varying wt% of ZrO2 nanoparticles are evaluated through abrasion and nanoindentation testing. Microstructural characterisation confirms reasonably uniform nanoparticle dispersion and notable grain refinement across the matrix. Progressive addition of reinforcement (0.5–2 wt%) results in significant improvements in microhardness (up to 39%), wear resistance, load-bearing capacity, and the formation of a stable tribo-layer during abrasion. Nanoindentation study reveals a 52.5% increase in nanohardness and a 35% enhancement in elastic modulus at AZ31-2 wt% ZrO2, confirming the effectiveness of the reinforcement in improving the mechanical integrity of the composite. Microstructural analysis of worn surfaces indicates a transition from severe abrasion and adhesion in the base alloy to dominant abrasive and oxidative wear in the composites. Additionally, the wear debris morphology evolves from long, ductile chips to fragmented, serrated particles with distinct shear bands, reflecting improved localised deformation resistance. These results demonstrate that nano-ZrO2 reinforcement significantly enhances the surface integrity and mechanical performance of AZ31, making it a promising candidate for lightweight, wear-resistant structural applications.
Goswami et al. (Thu,) studied this question.