Nanoindentation simulation of dislocation evolution in substrate/film systems

The dislocation evolution in substrate/film systems with Ag and Cu was investigated by the molecular dynamics simulation of nanoindentation. Film thickness in the range from 2 to 5 nm with the crystalline direction (001), which is the same as that of the substrate, was modelled in the present study. It was observed that the slip of the misfit dislocations in the interface is determined by indentation force and lattice constants of the substrate and the film. It was also shown that the crystal direction and the initial indentation position relative to misfit dislocation have a major role in the form of dislocation structures. The hardness of the bulk Cu is observed to be higher than that of the bulk Ag, as expected, however, it was also observed that soft film coating on the hard substrate cannot increase the hardness of the overall substrate/film system. On the contrary, the hard film, which is thicker than 4 nm, coating on the soft substrate increases the hardness of the overall substrate/film system.