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Title: Atomistic simulations of helium, hydrogen, and self-interstitial diffusion inside dislocation cores in tungsten

Abstract

Tritium retention and microstructural modifications due to helium accumulation are two of the main concerns regarding plasma-facing materials in fusion applications. Crystal defects in tungsten (W), such as grain boundaries and dislocations, can serve as traps or channels for diffusion of hydrogen (H) and helium (He), and, as such, can affect the transport of these species. In this work reported herein, we study the diffusion of hydrogen, helium and self-interstitial atoms (SIA) inside screw and edge dislocations in W using molecular dynamics simulations. Stable sites for interstitials in dislocations are identified using a free-volume analysis and energy barriers for diffusion are predicted using a combination of the nudged elastic band (NEB) method and finite temperature molecular dynamics simulations. Overall, the simulations predict higher energetic barriers for He and H diffusion in both screw and edge dislocations compared to the bulk. However, the diffusion mechanism in both dislocations are shown to differ: simulations predict that interstitials are constrained to move in short channels inside the edge dislocation core so that long-range diffusion along the dislocation line happens only with the motion of the dislocation. In contrast, 1D diffusion of the interstitial along the dislocation core, independent of dislocation motion, is observedmore » for screw dislocations.« less

Authors:
ORCiD logo [1]; ORCiD logo [1];  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR). Scientific Discovery through Advanced Computing (SciDAC); USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1604004
Report Number(s):
LA-UR-19-28989
Journal ID: ISSN 0029-5515; TRN: US2104174
Grant/Contract Number:  
89233218CNA000001; SC0008875; AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 60; Journal Issue: 2; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; dislocations; plasma facing materials; tungsten; interstitials; molecular dynamics; fusion reactor materials

Citation Formats

Mathew, Nithin, Perez, Danny, and Martinez Saez, Enrique. Atomistic simulations of helium, hydrogen, and self-interstitial diffusion inside dislocation cores in tungsten. United States: N. p., 2020. Web. doi:10.1088/1741-4326/ab6061.
Mathew, Nithin, Perez, Danny, & Martinez Saez, Enrique. Atomistic simulations of helium, hydrogen, and self-interstitial diffusion inside dislocation cores in tungsten. United States. https://doi.org/10.1088/1741-4326/ab6061
Mathew, Nithin, Perez, Danny, and Martinez Saez, Enrique. Fri . "Atomistic simulations of helium, hydrogen, and self-interstitial diffusion inside dislocation cores in tungsten". United States. https://doi.org/10.1088/1741-4326/ab6061. https://www.osti.gov/servlets/purl/1604004.
@article{osti_1604004,
title = {Atomistic simulations of helium, hydrogen, and self-interstitial diffusion inside dislocation cores in tungsten},
author = {Mathew, Nithin and Perez, Danny and Martinez Saez, Enrique},
abstractNote = {Tritium retention and microstructural modifications due to helium accumulation are two of the main concerns regarding plasma-facing materials in fusion applications. Crystal defects in tungsten (W), such as grain boundaries and dislocations, can serve as traps or channels for diffusion of hydrogen (H) and helium (He), and, as such, can affect the transport of these species. In this work reported herein, we study the diffusion of hydrogen, helium and self-interstitial atoms (SIA) inside screw and edge dislocations in W using molecular dynamics simulations. Stable sites for interstitials in dislocations are identified using a free-volume analysis and energy barriers for diffusion are predicted using a combination of the nudged elastic band (NEB) method and finite temperature molecular dynamics simulations. Overall, the simulations predict higher energetic barriers for He and H diffusion in both screw and edge dislocations compared to the bulk. However, the diffusion mechanism in both dislocations are shown to differ: simulations predict that interstitials are constrained to move in short channels inside the edge dislocation core so that long-range diffusion along the dislocation line happens only with the motion of the dislocation. In contrast, 1D diffusion of the interstitial along the dislocation core, independent of dislocation motion, is observed for screw dislocations.},
doi = {10.1088/1741-4326/ab6061},
journal = {Nuclear Fusion},
number = 2,
volume = 60,
place = {United States},
year = {Fri Jan 10 00:00:00 EST 2020},
month = {Fri Jan 10 00:00:00 EST 2020}
}

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