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Factors controlling segregation tendency of solute Ti, Ag and Ta into different symmetrical tilt grain boundaries of tungsten: First-principles and experimental study

Factors controlling segregation tendency of solute Ti, Ag and Ta into different symmetrical tilt grain boundaries of tungsten: First-principles and experimental study
Factors controlling segregation tendency of solute Ti, Ag and Ta into different symmetrical tilt grain boundaries of tungsten: First-principles and experimental study
In previous reports, experimental studies have shown that both thermal stability and strength can be controlled by grain boundary (GB) segregation. In this study, we investigate the segregation behavior of solute (Ti, Ag and Ta) atoms to low/high-angle symmetric tilt grain boundaries (STGBs) of W using density functional theory (DFT) calculations and supported by TEM experiments. We found no segregation preference for Ti or Ta at low-angle STGBs; however, they exhibit a slight segregation tendency to the core of high-angle STGBs. In contrast, Ag is more prone to segregate in and all around the GB plane. We estimated the mechanical and electronic contributions to solution energy and found that the electronic contribution is dominant. Furthermore, the role of valence electrons of solute and W atoms, was analyzed using the local density of states (PDOS). We found that substantial valence electrons hybridization in the case of Ta plays an important role in stabilizing W-Ta bonds, while the anisotropic nature of W-Ti bond contributes to stabilize surrounding W atoms. Charge transfer analysis revealed that Ti and Ta lose electrons to W atoms. Contrary to the electronegativity rule, Ag atoms gain charge from neighboring W atoms and excellent hybridization may explain the increased GB segregation of Ag atoms.
First-principles calculations, Grain boundaries, Ti/Ag/Ta segregation, Transmission electron microscopy (TEM), Tungsten
1359-6454
Polcar, Tomas
c669b663-3ba9-4e7b-9f97-8ef5655ac6d2
AlMotasem, Ahmed Tamer
ee76dbf7-7015-4928-988b-9c4f7c48045b
Huminiuc, Teodor
b743b7ba-7541-4f2e-b4be-ea25b088e4c6
Polcar, Tomas
c669b663-3ba9-4e7b-9f97-8ef5655ac6d2
AlMotasem, Ahmed Tamer
ee76dbf7-7015-4928-988b-9c4f7c48045b
Huminiuc, Teodor
b743b7ba-7541-4f2e-b4be-ea25b088e4c6

Polcar, Tomas, AlMotasem, Ahmed Tamer and Huminiuc, Teodor (2021) Factors controlling segregation tendency of solute Ti, Ag and Ta into different symmetrical tilt grain boundaries of tungsten: First-principles and experimental study. Acta Materialia, 211, [116868]. (doi:10.1016/j.actamat.2021.116868).

Record type: Article

Abstract

In previous reports, experimental studies have shown that both thermal stability and strength can be controlled by grain boundary (GB) segregation. In this study, we investigate the segregation behavior of solute (Ti, Ag and Ta) atoms to low/high-angle symmetric tilt grain boundaries (STGBs) of W using density functional theory (DFT) calculations and supported by TEM experiments. We found no segregation preference for Ti or Ta at low-angle STGBs; however, they exhibit a slight segregation tendency to the core of high-angle STGBs. In contrast, Ag is more prone to segregate in and all around the GB plane. We estimated the mechanical and electronic contributions to solution energy and found that the electronic contribution is dominant. Furthermore, the role of valence electrons of solute and W atoms, was analyzed using the local density of states (PDOS). We found that substantial valence electrons hybridization in the case of Ta plays an important role in stabilizing W-Ta bonds, while the anisotropic nature of W-Ti bond contributes to stabilize surrounding W atoms. Charge transfer analysis revealed that Ti and Ta lose electrons to W atoms. Contrary to the electronegativity rule, Ag atoms gain charge from neighboring W atoms and excellent hybridization may explain the increased GB segregation of Ag atoms.

Text
Factors controlling segregation tendency of solute Ti, Ag and Ta into different symmetrical tilt grain boundaries of tungsten First-principles and experimental study - Accepted Manuscript
Restricted to Repository staff only until 7 April 2022.
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Accepted/In Press date: 1 April 2021
e-pub ahead of print date: 7 April 2021
Keywords: First-principles calculations, Grain boundaries, Ti/Ag/Ta segregation, Transmission electron microscopy (TEM), Tungsten

Identifiers

Local EPrints ID: 450307
URI: http://eprints.soton.ac.uk/id/eprint/450307
ISSN: 1359-6454
PURE UUID: 768e61f0-791d-4ac8-b79d-220eb030c98e
ORCID for Tomas Polcar: ORCID iD orcid.org/0000-0002-0863-6287

Catalogue record

Date deposited: 21 Jul 2021 16:32
Last modified: 26 Nov 2021 02:57

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Contributors

Author: Tomas Polcar ORCID iD
Author: Ahmed Tamer AlMotasem
Author: Teodor Huminiuc

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