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Metals 2019, 9(2), 252; https://doi.org/10.3390/met9020252

Electronic Structure Calculations of Oxygen Atom Transport Energetics in the Presence of Screw Dislocations in Tungsten

1,2,3
,
2,3,*
and
1,4
1
Department of Materials Science and Engineering, University of California Los Angeles, Los Angeles, CA 90095, USA
2
Department of Metallurgy, Materials Science and Engineering, Institut Jean Lamour, Université de Lorraine, Campus ARTEM, Allée André Guinier, F-54011 Nancy, France
3
Laboratory of Excellence on Design of Alloy Metals for low-mAss Structures (DAMAS), Universitat de Lorraine, F-57073 Metz, France
4
Department of Mechanical and Aerospace Engineering, University of California Los Angeles, Los Angeles, CA 90095, USA
*
Author to whom correspondence should be addressed.
Received: 13 December 2018 / Revised: 12 February 2019 / Accepted: 15 February 2019 / Published: 20 February 2019
(This article belongs to the Special Issue Advanced Tungsten Materials)
Full-Text   |   PDF [1026 KB, uploaded 20 February 2019]   |  

Abstract

Plastic flow in body-centered cubic (bcc) alloys is governed by the thermally-activated motion of screw dislocations in close-packed planes. In bcc interstitial solid solutions, solute diffusion can occur at very fast rates owing to low migration energies and solute concentrations. Under mechanical loading, solutes may move on the same or similar time scale as dislocations glide, even at low temperatures, potentially resulting in very rich co-evolution processes that may have important effects in the overall material response. It is therefore important to accurately quantify the coupling between interstitial impurities and dislocations, so that larger-scale models can correctly account for their interactions. In this paper, we use electronic structure calculations to obtain the energetics of oxygen diffusion under stress and its interaction energy with screw dislocation cores in bcc tungsten. We find that oxygen atoms preferentially migrate from tetrahedral to tetrahedral site with an energy of 0.2 eV. This energy couples only weakly to hydrostatic and deviatoric deformations, with activation volumes of less than 0.02 and 0.02 b 3 , respectively. The strongest effect is found for the inelastic interaction between O atoms and screw dislocation cores, which leads to attractive energies between 1.2 and 1.9 eV and sometimes triggers a transformation of the screw dislocation core from an easy core configuration to a hard core configuration. View Full-Text
Keywords: W-O alloy; interstitial solid solution; screw dislocations; solute diffusion; stress coupling W-O alloy; interstitial solid solution; screw dislocations; solute diffusion; stress coupling
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Zhao, Y.; Dezerald, L.; Marian, J. Electronic Structure Calculations of Oxygen Atom Transport Energetics in the Presence of Screw Dislocations in Tungsten. Metals 2019, 9, 252.

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