Effect of SiC nanoparticle on microstructure and mechanical properties of graphene nanosheet (GNS) reinforced aluminum composites

Abstract

Homogeneous dispersion of high-content GNS is the challenge and key to achieve high mechanical properties of graphene reinforced aluminum matrix composites (GNS/Al). In traditional methods, the homogeneous dispersion of GNS is often achieved by prolonging the ball milling time or increasing the ball milling energy, which is often accompanied by severe damage to GNS structure. Here, a two-step ball milling process was employed to introduce SiC nanoparticles (SiCnp) in GNS/Al composites, which improves the GNS distribution while also playing an additional strengthening role. The Al flakes with a large lateral to thickness ratio were produced by a first-step ball milling of SiCnp and Al powders. The obtained Al flakes effectively improved the dispersion efficiency of GNS and reduced the GNS structural damage. As a consequence, GNS and SiCnp were well dispersed and combined with Al matrix after hot extrusion. The nanograins were also obtained in the extruded (GNS+SiCnp)/Al composites, which were conducive to the strengthening of composites. Benefiting from the homogeneous dispersion of GNS, SiCnp and the hybrid enhancement effect between them, the extruded (GNS+SiCnp)/Al composites showed significant improvement in Young’s modulus, tensile strength and, in particular, work hardening capacity compared to GNS/Al composites by approximately 278%, yielding good comprehensive mechanical properties.