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Title: Free energy change of a dislocation due to a Cottrell atmosphere

Abstract

The free energy reduction of a dislocation due to a Cottrell atmosphere of solutes is computed using a continuum model. In this work, we show that the free energy change is composed of near-core and far-field components. The far-field component can be computed analytically using the linearized theory of solid solutions. Near the core the linearized theory is inaccurate, and the near-core component must be computed numerically. The influence of interactions between solutes in neighbouring lattice sites is also examined using the continuum model. We show that this model is able to reproduce atomistic calculations of the nickel–hydrogen system, predicting hydride formation on dislocations. The formation of these hydrides leads to dramatic reductions in the free energy. Lastly, the influence of the free energy change on a dislocation’s line tension is examined by computing the equilibrium shape of a dislocation shear loop and the activation stress for a Frank–Read source using discrete dislocation dynamics.

Authors:
 [1];  [2]
  1. Sandia National Lab. (SNL-CA), Livermore, CA (United States); Stanford Univ., CA (United States). Dept. of Mechanical Engineering
  2. Stanford Univ., CA (United States). Dept. of Mechanical Engineering
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
OSTI Identifier:
1426811
Report Number(s):
SAND-2018-2133J
Journal ID: ISSN 1478-6435; 661000
Grant/Contract Number:  
AC04-94AL85000; SC0010412; NA0003525
Resource Type:
Accepted Manuscript
Journal Name:
Philosophical Magazine (2003, Print)
Additional Journal Information:
Journal Name: Philosophical Magazine (2003, Print); Journal Volume: 98; Journal Issue: 16; Journal ID: ISSN 1478-6435
Publisher:
Taylor & Francis
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 97 MATHEMATICS AND COMPUTING; 42 ENGINEERING; Dislocations; solid solutions; dislocation dynamics; hydrogen

Citation Formats

Sills, R. B., and Cai, W. Free energy change of a dislocation due to a Cottrell atmosphere. United States: N. p., 2018. Web. doi:10.1080/14786435.2018.1441560.
Sills, R. B., & Cai, W. Free energy change of a dislocation due to a Cottrell atmosphere. United States. doi:10.1080/14786435.2018.1441560.
Sills, R. B., and Cai, W. Wed . "Free energy change of a dislocation due to a Cottrell atmosphere". United States. doi:10.1080/14786435.2018.1441560. https://www.osti.gov/servlets/purl/1426811.
@article{osti_1426811,
title = {Free energy change of a dislocation due to a Cottrell atmosphere},
author = {Sills, R. B. and Cai, W.},
abstractNote = {The free energy reduction of a dislocation due to a Cottrell atmosphere of solutes is computed using a continuum model. In this work, we show that the free energy change is composed of near-core and far-field components. The far-field component can be computed analytically using the linearized theory of solid solutions. Near the core the linearized theory is inaccurate, and the near-core component must be computed numerically. The influence of interactions between solutes in neighbouring lattice sites is also examined using the continuum model. We show that this model is able to reproduce atomistic calculations of the nickel–hydrogen system, predicting hydride formation on dislocations. The formation of these hydrides leads to dramatic reductions in the free energy. Lastly, the influence of the free energy change on a dislocation’s line tension is examined by computing the equilibrium shape of a dislocation shear loop and the activation stress for a Frank–Read source using discrete dislocation dynamics.},
doi = {10.1080/14786435.2018.1441560},
journal = {Philosophical Magazine (2003, Print)},
number = 16,
volume = 98,
place = {United States},
year = {2018},
month = {3}
}

Journal Article:
Free Publicly Available Full Text
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Citation Metrics:
Cited by: 2 works
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Figures / Tables:

Figure 1 Figure 1: Cottrell atmospheres around edge dislocations. Contour lines show the solute concentration, $\chi$, in the nickel-hydrogen system at T = 300 K with a hydrogen concentration of $\chi$0 = 1.6 × 10−4 (160 at. ppm H): (a) when solute-solute interactions are neglected (Ess = 0) and (b) when solute-solutemore » interactions are included (Ess = −0.026 eV). (c) Atmosphere computed atomistically by von Pezold et al. [24] (reproduced with permission). Tick marks in (a,b) are in units of b. The scale for all three figures is identical.« less

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Works referenced in this record:

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    Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.