Interphase mechanical behaviours of graphene-copper nanocomposites: A study by in-situ nanoindentations and molecular dynamics simulations

The mechanical property of the interface between graphene and copper (Cu) plays crucial role in determining the overall mechanical performance of graphene-Cu nanocomposites. In this study, the distribution of mechanical properties near the Cu/graphene interface is systematically analysed through the in-situ nanoindentation tests and molecular dynamics (MD) simulations. The experimental results indicate that the influential region of the interface is around 40 mu m. The Young's modulus and hardness within this influential region can be significantly reduced by the interface effect, which can aggravate when closer to the interface. Our MD simulations indicate that the weakening effect of the interface on the mechanical properties is due to the weak graphene-Cu interaction and also the small out-of-plane stiffness of graphene, irrespective of the thickness of graphene. Based on the findings extracted from MD simulations, the theoretical models previously developed for the Young's modulus and hardness near the edge are extended to describe the distribution of the mechanical properties around the graphene/Cu interface. In general, this study on the mechanical properties near the graphene/Cu interface can provide the theoretical guidance for the design and application of graphene-Cu nanocomposites.