Characterization of the mechanical, tribological, and corrosion behaviour of ZrO ₂ -Cr ₂ O ₃ hybrid reinforced-aluminium matrix composites for automobile applications

Hybrid ceramic-reinforced aluminium matrix composites offer a promising pathway for achieving enhanced multifunctional performance in structural applications. In this study, equiatomic ZrO 2- Cr 2 O 3 hybrid-reinforced aluminium composites were successfully fabricated via a double-stage stir casting technique, with reinforcement levels of 0–7.5 wt.%. The novelty of this work lies in the synergistic integration of ZrO 2 and Cr 2 O 3 to simultaneously improve nanomechanical, tribological, and corrosion properties through optimized particle dispersion and interfacial interactions. Quantitative microstructural analysis using SEM and image-based particle size distribution revealed significant grain refinement and homogeneous dispersion at the optimal composition of 5 wt.% ZrO 2 –5 wt.% Cr 2 O 3 , with particle sizes reduced to the submicron range (0.121–2.8 µm). Nanoindentation results demonstrated enhanced stiffness, with a reduced elastic modulus of approximately 98 GPa, indicating superior load transfer capability compared to single-reinforced systems. Although a marginal decrease in hardness of about 1.7 GPa was observed relative to single ZrO 2 reinforcement, the hybrid system exhibited improved strength–toughness synergy due to combined mechanisms of transformation toughening, dislocation pinning, and effective stress distribution. Tribological analysis showed a reduction in wear rate with increasing reinforcement content, consistent with an abrasion-dominated wear mechanism, while electrochemical testing indicated improved corrosion resistance due to the inert and passivating nature of the hybrid oxides. The superior performance at the 5 wt.%ZrO 2 –5 wt.% Cr 2 O 3 composition is attributed to optimal interparticle spacing, minimized agglomeration, and enhanced interfacial bonding. This study demonstrates that ZrO 2 –Cr 2 O 3 hybridization provides a balanced improvement in stiffness, wear resistance, and corrosion performance, offering a viable design strategy for advanced aluminium matrix composites in demanding engineering applications.