Effects of graphene content on microstructures and tensile property of graphene-nanosheets / aluminum composites

Abstract

The graphene nanosheets (GNSs) reinforced Al matrix composites were successfully fabricated by high-energy ball milling and vacuum hot pressing. Effects of graphene content (0.25 wt%, 0.5 wt% and 1.0 wt%) on microstructures and tensile properties of GNSs/Al composites were investigated. Microstructures and the distribution of GNSs were analyzed with scanning electron microscope (SEM), X-ray diffraction (XRD) and transmission electron microscope (TEM). Tensile properties and hardness were studied at room temperature. The results show that the GNSs/Al composites with the high relative density and dispersed distribution of GNSs were fabricated. A good interfacial bonding was obtaned in GNSs/Al composites. The aluminum carbide Al4C3 phases with granular and short rod-like morphology were found at interface. With the increase of GNSs content, the content of Al4C3 phases increases. The dislocations were also found near the interface, and the density of dislocation reduced with the increase of Al4C3 content. The Vickers hardness of GNSs/Al composites increases obviously with the increase of GNSs content. The yield strength and ultimate tensile strength of GNSs/Al composites have an obvious improvement compared to that of pure Al, but the elongation show a slight decrease. The yield strength and ultimate tensile strength of Al-0.25GNSs composites increase by 38.27% and 56.19% compare with that of pure Al. The GNSs pull-out is detected at the edges of dimples, and the number of dimples slight decreases with the increase of GNSs content.