High strength and conductivity copper/graphene composites prepared by severe plastic deformation of graphene coated copper powder

In order to uniformly disperse graphene in the copper matrix, the complete coating of few-layers high-quality graphene on the surface of the copper powder was realized by chemical vapor deposition, and the graphene coated copper powder is sequentially formed through vacuum hot pressing, hot extrusion, and cold drawing processes. The results show that during the vacuum hot pressing, the metallurgical bonding between original copper powders is hindered by the graphene with a relatively complete structure. And the copper grains are recrystallized and refined in the hot extrusion process, and then stretched into a long and thin fibrous structure during the cold drawing process. Besides, the graphene is partially agglomerated during the hot extrusion pro-cess, and is dispersed again during the cold drawing process and gradually oriented along the drawing direction. Finally, the graphene and the copper matrix form a network interpenetrating structure, which improves the mechanical and electrical properties of the composite synergistically. The tensile strength and conductivity of the composite wire drawn to 1 mm reached 573.3 MPa and 5.79 x 10(7) S/m, respectively, achieving a breakthrough in the performance of copper-based materials.