Multiscale simulations of wedged nanoindentation on nickel

Mutiscale simulations of nanoindentation with different wedged indenters (with vertex angle from 120-170°) on the (-1 1 0) surface of nickel crystal were studied using the quasicontinuum method. Load-displacement responses, initial stages of the plasticity deformations and dislocation emissions for nickel film with each kind of indenter were obtained and analyzed as well. An elastic model based on the Hertz contact theory was proposed to analyze the critical vertex angle to emit dislocations. A critical vertex angle at the range of 156-162°was obtained. The Peierls-Nabarro dislocation model, as well as the elastic model and an energetic criterion were used to analyze the position of dislocations. A key parameter and its threshold values were obtained to characterize where the dislocation will be emitted. Simulation results matched well with analytical ones. This work is useful to research and understand the mechanism of dislocation emissions of nickel under wedged nanoindentation, and furthermore provides abilities to predict whether and where the dislocation will be emitted.