Atomistic Simulation of Creep in a Nanocrystal

Abstract

We describe a method to simulate on macroscopic time scales the stress relaxation in an atomistic nanocrystal model under an imposed strain. Using a metadynamics algorithm for transition state pathway sampling we follow the full evolution of a classical anelastic relaxation event, with relaxation times governed by the nanoscale microstructure imperfections in the solid. We show that probing this sensitive variation leads to mechanistic insights that reveal a direct correlation between system-level relaxation behavior and localized atomic displacements in the vicinity of the nanostructured defects, in turn implying a unit mechanism for self-organized plastic response. This suggests a new class of measurements in which the microstructure imperfections are characterized and matched to predictive simulations enabled by the present method.