Lattice Resistance to Dislocation Motion at the Nanoscale

TL;DR

This paper presents a model and simulations showing that free surfaces in nanoscale systems reduce lattice resistance, increasing dislocation velocity, with effects diminishing at higher stresses and temperatures.

Contribution

The paper introduces a new model quantifying how free surfaces influence lattice resistance and dislocation velocity at the nanoscale, supported by molecular dynamics simulations.

Findings

Surface proximity enhances dislocation velocity.

Lattice resistance decreases near free surfaces.

Higher stress and temperature reduce surface effects.

Abstract

In this letter we propose a model that demonstrates the effect of free surface on the lattice resistance experienced by a moving dislocation in nanodimensional systems. This effect manifests in an enhanced velocity of dislocation due to the proximity of the dislocation line to the surface. To verify this finding, molecular dynamics simulations for an edge dislocation in bcc molybdenum are performed and the results are found to be in agreement with the numerical implementations of this model. The reduction in this effect at higher stresses and temperatures, as revealed by the simulations, confirms the role of lattice resistance behind the observed change in the dislocation velocity.