Reinforcing or weakening? Determined by the interfacial nanostructures in graphene reinforced copper matrix composites

Graphene reinforced copper matrix composites (Gr/Cu) has been intensively studied, however, precisely controlling interfacial structure, understanding the reinforcing or weakening mechanism at nanoscale are still scientific problems by experiment method. Using a molecular dynamics simulation method, we examined the intrinsic relationship between nanostructures and evolutions mechanisms of various Gr/Cu composites. It was found that reinforcement of the Gr/Cu composites interface was dependent on its nanostructures. Under compression loading, interface with Gr/Cu{100} was more likely to experience a plastic deformation comparing to Gr/Cu{111} and Gr/Cu{110} interfaces. Graphene could lubricate the atoms migration at the Gr/Cu{100} interface but hinder these process at the Gr/Cu{111} and Cu{110} interfaces. Dislocation analysis confirmed that Shockly (1/6 〈112〉) dislocation was a main factor affecting the interface evolutions and dislocation propagation was limited by graphene sheets at the interface. Besides, the face-centred cubic (FCC) to hexagonal close-packed (HCP) transition induced by formation of stacking faults were observed to dominate in plastic deformation under higher compression strains to some extent, and the graphene sheet in grain boundaries could reverse the transition direction, which kept the plastic deformations under high compression strain more stable. Our findings may provide more insight to understand the interface characteristics-deformation relation of the graphene reinforced copper matrix composites.