Microstructure and mechanical properties of graphene nanoplates reinforced pure Al matrix composites prepared by pressure infiltration method

Highlights: • GNPs/pure Al composites have been prepared by the pressure infiltration method. • No Al₄C₃ phase was detected in the composites. • GNPs have been well bonded with the Al matrix. • Yield and tensile strength of the composites could be improved by the graphene. • The modified shear-lag model could explain the strengthening mechanism of the GNPs. In the present work, microstructure and mechanical behavior of the graphene nanoplates (GNPs) reinforced pure Al (GNPs/Al) composites prepared by the pressure infiltration method was investigated. No Al₄C₃ phase was detected in the composites, while GNPs have been well bonded with the Al matrix. It is suggested that the reaction between pure Al matrix and graphene could also be inhibited by using graphene with fewer defects. It has been found that the mechanical properties of the composites could be significantly improved by the addition of graphene. After addition of 0.54 wt% GNPs, the improvement of the yield and tensile strength before the extrusion was 116% and 45%, respectively. However, after the extrusion treatment, the corresponding increment of the yield and tensile strength was increased to 228% and 93%, respectively. Moreover, the fracture surface of the GNPs/Al composites before and after the extrusion treatment was mainly characterized by the lamellar structure with bridging of GNPs and the fine equiaxed structure with the pulling-out of the GNPs, respectively. Based on the modified shear-lag model, the strengthening mechanism of the GNPs/Al composites has been discussed, and the effect of GNPs and the extrusion treatment on the yield strength of the composites have been analyzed.