Bridging Atomistic and Continuum Descriptions of Nanoscale Dislocation Loops in Tungsten

TL;DR

This paper develops and verifies a linear elastic continuum model for nanoscale dislocation loops in tungsten, bridging atomistic and continuum descriptions to predict long-term irradiation effects.

Contribution

A verified linear elastic model informed by atomistic simulations that accurately captures far-field behavior of dislocation loops in tungsten.

Findings

Continuum model agrees with atomistic simulations in the far-field.

Decay rates of atomistic and continuum results match.

Results converge as atomistic simulation size increases.

Abstract

In order to predict the long-term effects of irradiation on the material properties of tungsten, a continuum approach to simulating the interactions of dislocation loops, which arise from radiation damage, is proposed. Continuum models of the displacement, strain and stress fields produced by dislocation loops exhibit unphysical singularities near the defect core, but are thought to accurately capture atomistic displacements in the far-field. A linear elastic model of nanoscale dislocation loops in tungsten is developed, and the model is verified using atomistic simulations to ensure that the model is informed by lower-length scale phenomena such that the physics of the problem is correctly captured. We discuss the model and its advantages, and show that predictions produced by atomistic simulations do indeed agree well with the far-field behaviour of the continuum model when dislocation loops are far from material boundaries. In particular, we robustly demonstrate that the decay rate of atomistic results and continuum results coincide with one another, and show that the results converge as the size of the atomistic simulations approach the far-field limit.