An atomistically validated continuum model for strain relaxation and misfit dislocation formation
In this paper, molecular dynamics (MD) calculations have been used to examine the physics behind continuum models of misfit dislocation formation and to assess the limitations and consequences of approximations made within these models. Without compromising the physics of misfit dislocations below a...
Saved in:
Published in | Journal of the mechanics and physics of solids Vol. 91; pp. 265 - 277 |
---|---|
Main Authors | , , , , , , |
Format | Journal Article Conference Proceeding |
Language | English |
Published |
United States
Elsevier Ltd
01.06.2016
|
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | In this paper, molecular dynamics (MD) calculations have been used to examine the physics behind continuum models of misfit dislocation formation and to assess the limitations and consequences of approximations made within these models. Without compromising the physics of misfit dislocations below a surface, our MD calculations consider arrays of dislocation dipoles constituting a mirror imaged “surface”. This allows use of periodic boundary conditions to create a direct correspondence between atomistic and continuum representations of dislocations, which would be difficult to achieve with free surfaces. Additionally, by using long-time averages of system properties, we have essentially reduced the errors of atomistic simulations of large systems to “zero”. This enables us to deterministically compare atomistic and continuum calculations. Our work results in a robust approach that uses atomistic simulation to accurately calculate dislocation core radius and energy without the continuum boundary conditions typically assumed in the past, and the novel insight that continuum misfit dislocation models can be inaccurate when incorrect definitions of dislocation spacing and Burgers vector in lattice-mismatched systems are used. We show that when these insights are properly incorporated into the continuum model, the resulting energy density expression of the lattice-mismatched systems is essentially indistinguishable from the MD results. |
---|---|
Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 AC04-94AL85000 SAND2015-7958C USDOE National Nuclear Security Administration (NNSA) |
ISSN: | 0022-5096 |
DOI: | 10.1016/j.jmps.2016.03.015 |