Nano-Indentation of Copper – Nickel thin films -A Molecular Dynamics Simulation Study

Abstract

Nanostructured materials have attracted many attentions and have been the subject of intensive research in recent years because they possess novel and/or enhanced mechanical properties compared with coarse grained materials. These enhanced mechanical properties of nanomaterial are an important subject of Nano-mechanics research. When brought into a bulk scale, nanoparticles can strongly affect the mechanical properties of the material, like stiffness or elasticity. The mechanical behaviour of very small volumes differs from what is typically observed on the macro level. In particular, thin metal films with nanometer-sized coatings possess interesting mechanical properties. Here, we have used molecular dynamics simulations to elucidate effect of Ni-thickness, effect of loading rate, effect of temperature on load-displacement behaviour during nanoindentation of thin copper films with nickel coatings. After simulation is being performed several deformation mechanisms, such as pile-up of dislocation at the interface, edge dislocation slip lines are observed. Most interestingly, the underlying copper films or substrates are significantly strengthened by thin nickel coatings. The strengthening effect is more pronounced at a low temperature.