Misfit dislocation network in Cu/Ni multilayers and its behaviors during scratching

The structure and distribution of misfit dislocations at Cu–Ni interfaces and their effects on the tribological behavior of a Ni film are investigated with 3D Molecular Dynamic Simulations. The structure of misfit dislocation network at a Cu–Ni interface differs according to different crystallographic orientations of the film relative to the substrate: a triangle and square type of misfit dislocation network are observed at (111)Cu||(111)Ni and (001)Cu||(001)Ni interfaces respectively. They play an important role in the strengthening of Cu/Ni multilayers. During the scratching of a single asperity contact on the Ni film, the misfit dislocation network becomes a significant barrier to the glide dislocations. The plot of friction force vs. normal load when scratching on the Ni film exhibits a horizontal stage, representing the decreasing of the frictional coefficient due to the existence of the misfit dislocations network.