Improved hardness and wear resistance in B ₄ C–SiC–TiC reinforced AA6061 composites produced by powder metallurgy: A comparative study of monolithic and hybrid structures

Aluminium matrix composites (AMCs) are increasingly used in wear-critical applications, yet improving their mechanical and tribological properties remains a key challenge. This study addresses this gap by investigating the effects of different ceramic reinforcements—silicon carbide (SiC), boron carbide (B 4 C), and titanium carbide (TiC)—on the microstructure, hardness, and wear behaviour of AA6061-based monolithic and hybrid composites. The composites were fabricated using the powder metallurgy method, followed by compaction and sintering. Microstructural analysis revealed a uniform distribution of reinforcements and good interfacial bonding. The results showed that increasing the reinforcement ratio significantly enhanced hardness, with B 4 C providing the greatest improvement due to its high thermal stability and strong bonding characteristics. The AA6061/B 4 C monolithic composite exhibited an 85.7% increase in hardness, while the AA6061/SiC/B 4 C hybrid composite showed a 101.2% increase. Similarly, wear resistance improved by 46% and 47% for the B 4 C and B 4 C + SiC reinforced composites, respectively, due to the synergistic reinforcement effect. All samples showed successful densification, with relative densities between 92% and 97%, and porosity ranging from 3% to 8%. The coefficient of friction remained stable (0.1–0.2) across all samples. These findings demonstrate that B 4 C, especially when combined with SiC, is a highly effective reinforcement strategy for enhancing the performance of AA6061 matrix composites.