Effect of graphene sheet diameter on the microstructure and properties of copper-plated graphene-reinforced 6061-aluminum matrix composites

Herein, graphene with two different average sheet diameters was ultrasonically dispersed, mechanically stirred, and copper-plated. The pretreated graphene was mixed with 6061-aluminum (6061Al) powder to fabricate copper-plated graphene (0.5 wt%) reinforced 6061Al matrix composites by spark plasma sintering. The resulting composites were characterized in terms of their microstructure, tensile properties, electrical conductivity, and thermal conductivity. The incorporation of graphene facilitated load transfer and hindered dislocation movement, thereby enhancing the mechanical properties of the composites. Notably, the composite reinforced by larger-sized graphene achieved a favorable combination of high tensile strength (218 MPa) and fracture strain (17.2 %). Moreover, the addition of graphene also ameliorated the electrical conductivity of 6061Al. The composite reinforced by the larger-sized graphene achieved the highest electrical conductivity of 47.7 %IACS, attributed to the formation of a wider range of conductive channels. Additionally, the introduction of larger-sized graphene increased the thermal conductivity of 6061Al from 161.4 W/(m·K) to 183.2 W/(m·K), whilst the smaller-sized graphene contributed to a modest enhancement of 15.3 W/(m·K). In conclusion, graphene with a larger sheet diameter exhibits a remarkable reinforcement effect on the overall performance of 6061Al.