A novel approach for in-situ preparation of copper/graphene composite with high hardness and high electrical conductivity

•High-performance Cu/graphene-Al2O3 composite is in-situ prepared by hot-press sintering.•Aluminum isopropoxide is chosen as the carbon source to in-situ generated Graphene and Al2O3.•In-situ formed Graphene and Al2O3 strengthen the matrix and improve the Cu/C interface bonding.•The Cu/Graphene-Al2O3 possesses high strength, electrical conductivity and softening resistance. A bulk Cu/graphene-Al2O3 composite with high electrical conductivity (96.95% IACS) and high hardness (87.21 HV) was successfully fabricated through vacuum hot pressing sintering by introducing aluminum isopropoxide as the carbon source. The in-situ formed graphene with high-quality distributes along the grain boundary, the nano sized Al2O3 particles generated near the interface. Both graphene and Al2O3 nano particles greatly refine the microstructure of the Cu/graphene composite and strengthen the matrix. The cold rolled Cu/graphene-Al2O3 sheet presents high electrical conductivity and high strength. The coexistence of graphene and Al2O3 nano particles blocks the movement of grain boundaries, delays the recovery and recrystallization process of the Cu matrix and makes the composite possess excellent softening resistance. The work provides a new idea for large-scale preparation of high-performance Cu/graphene composites.