Improved strength-plasticity-conductivity of graphene/copper layered composites by vacuum hot rolling

The method used to strengthen copper matrix composites generally results in a significant decrease in ductility and electrical conductivity. In this work, multilayer graphene was grown on both sides of copper foil using chemical vapor deposition process and graphene/copper layered composites were prepared by stacking copper foils and hot rolling under vacuum. The microstructures, mechanical properties and electrical conductivity of hot rolled graphene/copper layered composites with different reduction amounts were investigated. Results showed that the grain size increased while the dislocation density did not change much with the reduction amounts from 30% to 50%. The size of graphene decreased and the spacing of graphene increased with the reduction amounts. When the reduction amounts increased from 30% to 50%, the tensile strength decreased from 223 MPa to 163 MPa, the elongation decreased from 45% to 31% and the electrical conductivity decreased from 101.52 %IACS to 89.73 %IACS. The optimized combination of properties was obtained when the hot rolled reduction amount was set as 30% because of the grain refining and the change in graphene size and spacing. Combining the analysis of microstructures and properties of the unreinforced copper matrix at 30% reduction amount, it can be concluded that the tensile strength of the composite increased from 179 MPa to 223 MPa, elongation increased from 38% to 45% and electrical conductivity increased from 98.02 %IACS to 101.52 %IACS. Long and distributed continuously graphene were beneficial to the improvement of strength, elongation and electrical conductivity by playing an obvious role in the load transfer strengthening mechanism, refining the grain size of the composites, and preventing the crack propagation.