An Evaluation of Atomic Force Microscopy as a Probe of Nanoscale Residual Stress Via Atomistic Simulation

Abstract

Results from a series of molecular dynamics simulations are reported in which a nanoscale tip was used to indent gold lattices subjected to external strains. The changes in the slope of the loading curves reflect the stress state of the sample. This was true even in the absence of material pile-up, suggesting that the change in loading reflects changes in elastic properties of materials and not a change in contact area due to pile-up. Shallow nanoindentation was also evaluated as a method to map residual surface stresses by simulating indentation at a series of points near a dislocation intersecting a surface. Correlations between the maximum force on the tip and the initial local stresses at the point of indentation were observed. Thus, preliminary atomistic simulations indicate that atomic-force microscopy can be used as a nondestructive, nanoscale probe of the surface stress distributions