Effect of dual reinforcement and stir casting process parameters on the fretting wear response of Al7075–B ₄ C–BFS hybrid composites

This study investigates the influence of dual reinforcement using 3 wt.% boron carbide (B 4 C, ∼150 µm) and blast furnace slag (BFS) at 0–10 wt.% on the mechanical and fretting wear behavior of Al7075 hybrid metal matrix composites produced by stir casting. Composites with varying reinforcement combinations were evaluated for density, hardness, tensile strength, and fretting wear performance under room and elevated temperatures in accordance with ASTM standards. The results show that the hybrid composite containing 8 wt% B 4 C and 4 wt% BFS exhibited the highest improvements in hardness (118 ± 2.48 Hv) and tensile strength (250 ± 8.25 MPa). At 50 N, 20 mm, and RT, the wear rate decreased from 0.00762 ± 0.00048 mm 3 /(Nm) (S1) to 0.00449 ± 0.00029 mm 3 /(Nm) (S4), representing a ∼41% reduction. Similar trends were observed at elevated loads and temperatures, confirming the thermally stable and load-bearing nature of the dual-reinforced composite. SEM analyses of worn surfaces revealed the formation of a mechanically mixed, oxide-rich tribolayer that contributed to reduced material removal. Overall, the Al7075–3%B 4 C–10%BFS (S4) composite demonstrated the best balance of mechanical strength, thermal stability, and wear resistance. The study demonstrates that incorporating industrial waste–derived BFS along with B 4 C offers a cost-effective and sustainable route to enhance fretting wear resistance in Al7075 alloys identifying optimal reinforcement combinations for aerospace and automotive components subjected to cyclic micro-sliding and elevated temperatures.