Multiscale Modeling of Nanoindentation: Significance of Local Temperature

A dynamic multiscale (MD/FE) method has been used to study dislocation generation and plastic deformation during a nanoindentation process which is physically associated with the generation of heat within the specimen and as a consequence with a temperature rise. Two different techniques are applied to study the temperature effect on the nanoindention process. In the first technique, a global Nose-Hoover thermostat is applied to the entire atomistic region to keep temperature constant during simulation (finite temperature approach). In the second method, the thermostat is applied only on a damping region along the MD/FE interface. Both techniques are able to effectively and efficiently absorb high frequency reflected waves from atomistic/continuum interface. The temperature profile of the atomistic region beneath the indenter is reported and discussed at four different initial substrate temperatures for both techniques. The loaddisplacement (load/unload) curves for different temperature-controlling techniques are compared and discussed. The nucleation and propagation of dislocations in the atomistic region are investigated for both techniques. Correlations between the observed features in the load-displacement curves with the motion and pile-up of dislocations are reported as a function of temperature.