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Title: Mesoscale modeling of vacancy-mediated Si segregation near an edge dislocation in Ni under irradiation

Authors:
;
Publication Date:
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1351121
Grant/Contract Number:
FG02-05ER46217
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 95; Journal Issue: 14; Related Information: CHORUS Timestamp: 2017-04-11 22:11:45; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society
Country of Publication:
United States
Language:
English

Citation Formats

Li, Zebo, and Trinkle, Dallas R. Mesoscale modeling of vacancy-mediated Si segregation near an edge dislocation in Ni under irradiation. United States: N. p., 2017. Web. doi:10.1103/PhysRevB.95.144107.
Li, Zebo, & Trinkle, Dallas R. Mesoscale modeling of vacancy-mediated Si segregation near an edge dislocation in Ni under irradiation. United States. doi:10.1103/PhysRevB.95.144107.
Li, Zebo, and Trinkle, Dallas R. Tue . "Mesoscale modeling of vacancy-mediated Si segregation near an edge dislocation in Ni under irradiation". United States. doi:10.1103/PhysRevB.95.144107.
@article{osti_1351121,
title = {Mesoscale modeling of vacancy-mediated Si segregation near an edge dislocation in Ni under irradiation},
author = {Li, Zebo and Trinkle, Dallas R.},
abstractNote = {},
doi = {10.1103/PhysRevB.95.144107},
journal = {Physical Review B},
number = 14,
volume = 95,
place = {United States},
year = {Tue Apr 11 00:00:00 EDT 2017},
month = {Tue Apr 11 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevB.95.144107

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  • Atomistic simulations of segregation to a dissociated (a{sub 0}/2)[1{bar 1}] edge dislocation in the solid solution alloy Cu{sub 0.1}Ni{sub 0.9} have been performed. Segregation to the stacking fault between the partials is minimal. Results obtained with a general embedded atom method potential and one optimized for the Ni-Cu system differ significantly. Simulations employing the optimized potentials show significantly more Cu segregation to the dislocation cores than do simulations performed with the general potentials. When the general potentials are employed, the Cu concentration around the dislocation is well described using classical segregation isotherms based upon the stress distribution around the dislocation,more » except in the dislocation core region. Deviations from the theoretically predicted segregation profile around the dislocation core are largest along the slip plane. When the optimized potentials are used, the deviations from the predicted segregation behavior are significantly larger. The large deviations associated with the optimized potentials were traced to the inadequacy of describing the local heat of segregation in terms of the elastic work {sigma}{sub h}{Delta}V. This can be rectified by adding a term to the heat of segregation that explicitly includes the composition dependence. The failure of the classical segregation isotherm to describe the segregation behavior around a dislocation is associated with non-ideal alloy thermodynamics and the inadequacy of linear elasticity to appropriate describe the core region of the dislocation. The failure of the classical segregation isotherm within the core appears to result from the fact that the core atoms have different atomic coordination than those in the bulk material.« less
  • The authors have investigated the solute segregation and simultaneous evolution of extended defects in an Fe-Cr-Ni alloy during irradiation by computer simulation. It sheds a light on the accomplishment of performing the combined total calculation or the multiscale modeling which deals with both radiation-induced segregation and various kinds of internal sink evolution. The formation of dislocation-free zone (DLFZ) was predicted in the vicinity of a grain boundary. It indicated that DLFZ formation is controlled by solute diffusional process via point defects diffusion near the grain boundary and the activation energy obtained by the width of DLFZ corresponds to the halfmore » of the value of the radiation-enhanced solute diffusivity.« less
  • Multiscale atmospheric simulations can be computationally prohibitive, as they require large domains and fine spatiotemporal resolutions. Grid-nesting can alleviate this by bridging mesoscales and microscales, but one turbulence scheme must run at resolutions within a range of scales known as the terra incognita (TI). TI grid-cell sizes can violate both mesoscale and microscale subgrid-scale parametrization assumptions, resulting in unrealistic flow structures. Herein we assess the impact of unrealistic lateral boundary conditions from parent mesoscale simulations at TI resolutions on nested large eddy simulations (LES), to determine whether parent domains bias the nested LES. We present a series of idealized nestedmore » mesoscale-to-LES runs of a dry convective boundary layer (CBL) with different parent resolutions in the TI. We compare the nested LES with a stand-alone LES with periodic boundary conditions. The nested LES domains develop ~20% smaller convective structures, while potential temperature profiles are nearly identical for both the mesoscales and LES simulations. The horizontal wind speed and surface wind shear in the nested simulations closely resemble the reference LES. Heat fluxes are overestimated by up to ~0.01 K m s-1 in the top half of the PBL for all nested simulations. Overestimates of turbulent kinetic energy (TKE) and Reynolds stress in the nested domains are proportional to the parent domain's grid-cell size, and are almost eliminated for the simulation with the finest parent grid-cell size. Based on these results, we recommend that LES of the CBL be forced by mesoscale simulations with the finest practical resolution.« less
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  • Arsenic diffusion has been studied at 1000 deg. C in Si and relaxed Si{sub 0.9}Ge{sub 0.1} structures grown using molecular beam epitaxy. Intrinsic diffusivity of As in Si{sub 0.9}Ge{sub 0.1} is shown to be enhanced over Si by a factor of 2, in agreement with the literature. Using selective point defect injection, obtained by surface reactions achieved using rapid thermal annealing process under oxygen atmosphere, clear evidence of the participation of both vacancy and interstitial defects in the diffusion process of As in Si as well as Si{sub 0.9}Ge{sub 0.1} is obtained. Qualitatively, a higher contribution of vacancies in Si{submore » 0.9}Ge{sub 0.1} than in Si is apparent.« less