Synergistic effect of B ₄ C and graphene nanoparticles on the mechanical and tribological properties of Al-Fe-Si hybrid nano composites

This study investigates the synergistic effect of boron carbide (B 4 C) and graphene nanoparticles (GNPs) on the mechanical and tribological properties of AA8011-based aluminum composites. Hybrid composites containing 6 wt% B 4 C and varying graphene contents (0.5–1.5 wt%) were fabricated via ultrasonic-assisted stir casting to ensure uniform particle distribution. Microstructural analysis confirmed homogeneous dispersion at optimal graphene loading, while excessive addition led to agglomeration. The results reveal substantial improvements in mechanical properties: hardness increased from 54.72 HV (S1) to 87.21 HV (S4), a 59.4% rise, while tensile strength improved from 107.86 MPa to 193.3 MPa (79.1% increase), and Yield strength rose from 78.16 MPa to 171.04 MPa (118.8% increase), attributed to grain refinement, and effective load transfer mechanisms. However, ductility reduced from 18.26% to 6.5%, a 64.4% drop, reflecting the strength–ductility trade-off. Tribological evaluation revealed notable reductions in wear rate by ∼55% and coefficient of friction decreased by ∼36% at 1 wt.% graphene due to the formation of a stable graphene-rich tribofilm. However, further graphene addition caused clustering, leading to a marginal decline in performance. The synergy of B 4 C and graphene in AA8011 alloy delivers lightweight composites with optimally balanced strength and wear resistance for advanced engineering applications.