Mechanical behaviors of graphene/copper matrix composite foils fabricated by pulse electrodeposition

The Graphene/copper matrix (Gr/Cu) composite foils were successfully fabricated by pulse electrodeposition from copper sulfate solution containing graphene nanoplates ranging from 0.04 to 1.6g/L. The morphology, microstructure, tensile properties and nanoindentation hardness of Gr/Cu composite foils were characterized. The results indicated that the few-layer graphene nanoplates were distributed in nanotwined Cu matrix, Gr/Cu composite foils existed in the form of graphene nanoplates wrapped by Cu grains. With the increase of graphene concentration in electrolyte, the tensile strength of Gr/Cu composite foil decreased from 367 to 236 MPa, then increased up to 274 MPa. Similarly, the hardness decreased from 2.02 to 1.44 GPa, and then increased up to 1.71 GPa. Then, the crystalline size (d) calculated based on the XRD patterns changed from 520 to 890 nm and then decreased to 710 nm. The variation of tensile strength and hardness was mainly attributed to the change of the crystalline size. Besides, graphene defects of Gr/Cu composite foils were taken into account to explain the change of tensile strength and hardness. The models for tensile strength, hardness and graphene concentration were proposed to evaluate the tensile strength and hardness of Gr/Cu composite foils.