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Title: Nanoscale dislocation shear loops at static equilibrium and finite temperature

Abstract

Atomistic simulations are used to determine the resolved shear stress necessary for equilibrium and the resulting geometry of nanoscale dislocation shear loops in Al. Dislocation loops with different sizes and shapes are created via superposition of elemental triangular dislocation displacement fields in the presence of an externally imposed shear stress. First, a bisection algorithm is developed to determine systematically the resolved shear stress necessary for equilibrium at 0 K. Here, this approach allows for the identification of dislocation core structure and a correlation between dislocation loop size, shape and the computed shear stress for equilibrium. It is found, in agreement with predictions made by Scattergood and Bacon, that the equilibrium shape of a dislocation loop becomes more circular with increasing loop size. Second, the bisection algorithm is extended to study the influence of temperature on the resolved shear stress necessary for stability. An approach is presented to compute the effective lattice friction stress, including temperature dependence, for dislocation loops in Al. The temperature dependence of the effective lattice friction stress can be reliably computed for dislocation loops larger than 16.2 nm. However, for dislocation loops smaller than this threshold, the effective lattice friction stress shows a dislocation loop size dependencemore » caused by significant overlap of the stress fields on the interior of the dislocation loops. Combined, static and finite temperature atomistic simulations provide essential data to parameterize discrete dislocation dynamics simulations.« less

Authors:
 [1];  [2]; ORCiD logo [1]
  1. Univ. of Florida, Gainesville, FL (United States). Dept. of Mechanical & Aerospace Engineering
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC). Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1483516
Report Number(s):
LA-UR-18-22973
Journal ID: ISSN 0965-0393
Grant/Contract Number:  
89233218CNA000001
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Modelling and Simulation in Materials Science and Engineering
Additional Journal Information:
Journal Volume: 25; Journal Issue: 8; Journal ID: ISSN 0965-0393
Publisher:
IOP Publishing
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; dislocation

Citation Formats

Dang, Khanh, Capolungo, Laurent, and Spearot, Douglas E. Nanoscale dislocation shear loops at static equilibrium and finite temperature. United States: N. p., 2017. Web. doi:10.1088/1361-651X/aa9390.
Dang, Khanh, Capolungo, Laurent, & Spearot, Douglas E. Nanoscale dislocation shear loops at static equilibrium and finite temperature. United States. doi:10.1088/1361-651X/aa9390.
Dang, Khanh, Capolungo, Laurent, and Spearot, Douglas E. Mon . "Nanoscale dislocation shear loops at static equilibrium and finite temperature". United States. doi:10.1088/1361-651X/aa9390. https://www.osti.gov/servlets/purl/1483516.
@article{osti_1483516,
title = {Nanoscale dislocation shear loops at static equilibrium and finite temperature},
author = {Dang, Khanh and Capolungo, Laurent and Spearot, Douglas E.},
abstractNote = {Atomistic simulations are used to determine the resolved shear stress necessary for equilibrium and the resulting geometry of nanoscale dislocation shear loops in Al. Dislocation loops with different sizes and shapes are created via superposition of elemental triangular dislocation displacement fields in the presence of an externally imposed shear stress. First, a bisection algorithm is developed to determine systematically the resolved shear stress necessary for equilibrium at 0 K. Here, this approach allows for the identification of dislocation core structure and a correlation between dislocation loop size, shape and the computed shear stress for equilibrium. It is found, in agreement with predictions made by Scattergood and Bacon, that the equilibrium shape of a dislocation loop becomes more circular with increasing loop size. Second, the bisection algorithm is extended to study the influence of temperature on the resolved shear stress necessary for stability. An approach is presented to compute the effective lattice friction stress, including temperature dependence, for dislocation loops in Al. The temperature dependence of the effective lattice friction stress can be reliably computed for dislocation loops larger than 16.2 nm. However, for dislocation loops smaller than this threshold, the effective lattice friction stress shows a dislocation loop size dependence caused by significant overlap of the stress fields on the interior of the dislocation loops. Combined, static and finite temperature atomistic simulations provide essential data to parameterize discrete dislocation dynamics simulations.},
doi = {10.1088/1361-651X/aa9390},
journal = {Modelling and Simulation in Materials Science and Engineering},
issn = {0965-0393},
number = 8,
volume = 25,
place = {United States},
year = {2017},
month = {11}
}

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Cited by: 2 works
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