ABSTRACT

A large-scale atom simulation of nanoindentation into a thin nickel film using the quasicontinuum method was performed. The initial stages of the plasticity deformation of nickel were studied. Several useful results were obtained as follows: (1) The response of the load versus indentation depth - on the load versus indentation depth curve, besides the straight parts corresponding to the elastic property of nickel, the sudden drop of the load occurred several times; (2) The phenomena of dislocation nucleation - the dislocation nucleation took place when the load descended, which makes it clear that dislocation nucleation causes the drop of the load; (3) The mechanism of the dislocation emission - the Peierls-Nabarro dislocation model and a powerful criterion were used to analyze the dislocation emission. And the computational value was in good agreement with the predict value; (4) The density of geometrically necessary dislocations. A simple model was used to obtain the density of geometrically necessary dislocations beneath the indenter. Furthermore, the influence of the boundary conditions on the simulation results was discussed.