High strength and conductivity copper matrix composites reinforced by in-situ graphene through severe plastic deformation processes

The dispersion of graphene in copper matrix and their interfacial bonding quality decisively determine the comprehensive performance of graphene/copper composites. To explore the possibility of dispersing the well-bonded graphene evenly in the copper matrix, we tested various processing methods and obtained a unique copper-based composite reinforced by in-situ graphene, achieved by two severe plastic deformation processes of hot extrusion and cold drawing. The experimental results revealed that the in-situ graphene was in the form of shreds and uniformly dispersed in the copper matrix. The abnormal coarsening of copper grains occurred during the graphene depositing process due to high temperature, but the grains were then refined during the following severe plastic deformation process. Graphene can play a role of pinning dislocations and hindering grain boundary slip, thereby improving the strength of the composite. Meanwhile, the network structure of graphene in the copper matrix provides a fast path for electron transmission which can make up for the negative effect of the fine of copper grain structure on the conductivity. The tensile strength and conductivity of the composite reach to 595 MPa and 5.46 x 10(7) S/m, representing an increase of 23.4% in tensile strength, and similar conductivity (98%) of the original copper matrix. (C) 2020 Elsevier B.V. All rights reserved.