Effects of cobalt content on the microstructural and mechanical/electrical properties of graphene reinforced copper matrix composites

The microstructures and the mechanical/electrical properties of graphene nanoplates-copper (GNPs-Cu; 0.4 wt%) composites and the composites doped by cobalt (GNPs: 0.4 wt%; Co: 2, 3, 4 wt%) have been researched, which have been prepared by mechanical alloying and spark plasma sintering (SPS) technology. It is found that GNPs disperse evenly in Cu matrix with the ball milling time of 6 h. The compressive strength and the hardness of GNPs-Cu are 601.88 MPa and 128 HV, respectively, which were increased by 3 times and 42.2% compared to pure Cu. And the IACS of the GNPs-Cu composites was 79%. The GNPs-Cu composites with 3 wt% Co (3 wt% Co-GNPs-Cu) also present excellent mechanical properties. The compressive strength and the hardness is 571.32 MPa and 145 HV, respectively, which is raised by 2.81 times and 61.1% compared to pure Cu. And the IACS of the 3 wt% Co-GNPs-Cu composites is 65%. In addition, based on the first principle calculation the mechanism of the effect of Co doping on the GNPs-Cu interface bonding has been studied. Our results provide experimental basis for the preparation of high strength and high conductivity Cu matrix composites, which can be widely used in many fields, such as high-strength magnetic field, heat exchange material, etc.