Scale-free phase field theory of dislocations

TL;DR

This paper introduces a scale-free phase field continuum theory for modeling dislocation distributions near boundaries in submicron crystals, capturing boundary effects without intrinsic length scales.

Contribution

It presents a novel scale-free phase field model for dislocation dynamics near boundaries, aligning with discrete simulations without using length scale parameters.

Findings

Successfully reproduces boundary dislocation distributions

Captures scale-free $1/r$ dislocation interactions

Applicable to submicron crystal deformation studies

Abstract

According to recent experimental and numerical investigations if the characteristic size of a specimen is in the submicron size regime several new interesting phenomena emerge during the deformation of the samples. Since in such a systems the boundaries play a crucial role, to model the plastic response of submicron sized crystals it is crucial to determine the dislocation distribution near the boundaries. In this paper a phase field type of continuum theory of the time evolution of an ensemble of parallel edge dislocations with identical Burgers vectors, corresponding to the dislocation geometry near boundaries, is presented. Since the dislocation-dislocation interaction is scale free ($1/r$), apart from the average dislocation spacing the theory cannot contain any length scale parameter. As shown, the continuum theory suggested is able to recover the dislocation distribution near boundaries obtained by discrete dislocation dynamics simulations.