Achieving balanced properties in graphene/Cu composite with oriented bimodal grains: Strength, ductility, and conductivity

In the pursuit of advanced materials with multifunctional capabilities, graphene-based composites have gained substantial attention due to their exceptional mechanical, electrical properties, etc. In this paper, we present a straightforward method for fabricating graphene/Cu composites with an oriented bimodal structure through an in-situ synthesis process combined with hot rolling. Dendritic copper powder, mechanical exfoliation graphene and polyacrylonitrile were used as the raw materials. The graphene/Cu composite with oriented bimodal grains achieves a good balance between strength, ductility and electrical conductivity. Both the fine grains arising from the raised fine particles of dendritic copper powder and the graphene coated on the surface of fine grains facilitate the load transfer, resulting in improved strength of the composites. Furthermore, the formation of coarse grains during sintering and hot rolling deformation contributes to enhanced ductility. Simultaneously, the oriented structure of these coarse grains and graphene sheets establishes an efficient charge transport pathway, ensuring high electrical conductivity. The tensile yield strength of the oriented bimodal composite measures 315 MPa with 0.073 wt% carbon content, while its fracture elongation is 12.4%, and the electrical conductivity remains at 95.7% IACS. This study not only sheds light on the synergistic effects between graphene and copper in a bimodal composite system but also introduces a methodology for tailoring the microstructure to achieve a desired balance between mechanical strength, ductility, and electrical conductivity.