Influence of Graphene, SiC Np , and G/SiC Np Hybrid Fillers on the Strengthening Mechanisms of Al-Matrix

AA2124 reinforced with graphene (G), silicon carbide nanoparticles (SiC np ), and graphene-coated SiC np (GCSiC np ) were fabricated and characterized. GCSiC np reinforcement was fabricated by ball milling, followed by mixing and milling the reinforcements with AA2124 powders. Consolidation was achieved by cold compaction and hot extrusion (HE). The powders’ morphology and structural evolution were characterized with XRD and SEM. Microhardness and tensile properties were also characterized. Increasing the fillers’ content beyond 5 wt pct deteriorated the composites’ mechanical properties due to the agglomeration of the fillers. Adding 5 wt pct GCSiC np increased the hardness, specific strength, and modulus of the composite and decreased ductility. Furthermore, 5 wt pct SiC np induced severe lattice strain by intra-granular dispersion strengthening. The GCSiC np filler strengthened the Al-matrix via the strong interfacial bonding of the intercalated inter-granular lamination of the hybrid particles within the Al-matrix and the intra-granular dispersion strengthening associated with the individual SiC np . Adding 5 wt pct G lowered the HE composite’s density and hardness significantly, while the sliding of G-intercalated layers coating the Al-grains facilitated plastic flow along the extrusion direction and enhanced the strength and ductility of the composite compared to that containing 5 wt pct GCSiC np .