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 nearcore and farfield components. The farfield component can be computed analytically using the linearized theory of solid solutions. Near the core the linearized theory is inaccurate, and the nearcore 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:

 Sandia National Lab. (SNLCA), Livermore, CA (United States); Stanford Univ., CA (United States). Dept. of Mechanical Engineering
 Stanford Univ., CA (United States). Dept. of Mechanical Engineering
 Publication Date:
 Research Org.:
 Sandia National Lab. (SNLNM), Albuquerque, NM (United States)
 Sponsoring Org.:
 USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC22). Materials Sciences & Engineering Division
 OSTI Identifier:
 1426811
 Report Number(s):
 SAND20182133J
Journal ID: ISSN 14786435; 661000
 Grant/Contract Number:
 AC0494AL85000; 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 14786435
 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 nearcore and farfield components. The farfield component can be computed analytically using the linearized theory of solid solutions. Near the core the linearized theory is inaccurate, and the nearcore 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}
}
Web of Science
Figures / Tables:
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Works referencing / citing this record:
Influence of hydrogen core force shielding on dislocation junctions in iron
journal, March 2020
 Yu, Haiyang; Katzarov, Ivaylo H.; Paxton, Anthony T.
 Physical Review Materials, Vol. 4, Issue 3
Figures / Tables found in this record: