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Phosphorus driven embrittlement and atomistic crack behavior in tungsten grain boundaries

Hiremath, Praveenkumar LU ; Melin, Solveig LU and Olsson, Pär LU (2024) In Computational Materials Science 244.
Abstract
We investigated the role of phosphorus (P) impurities on the fracture toughness and underlying failure mechanisms by means of classical atomistic modeling for a set of ⟨110⟩ symmetric tilt tungsten grain boundaries (GBs). This entailed the utilization of a quasi-static mode I displacement-controlled setup with cohesive zone volume elements (CZVEs) to study failure mechanisms and evaluate the fracture toughness of the GB cracks. The fracture toughness was estimated using three approaches: computing (i) the individual and (ii) the average energy release rate of CZVEs along the fractured surfaces and using them as inputs for the Griffith model, and (iii) relating the fracture toughness to crack propagation initiation. The cracks in all the... (More)
We investigated the role of phosphorus (P) impurities on the fracture toughness and underlying failure mechanisms by means of classical atomistic modeling for a set of ⟨110⟩ symmetric tilt tungsten grain boundaries (GBs). This entailed the utilization of a quasi-static mode I displacement-controlled setup with cohesive zone volume elements (CZVEs) to study failure mechanisms and evaluate the fracture toughness of the GB cracks. The fracture toughness was estimated using three approaches: computing (i) the individual and (ii) the average energy release rate of CZVEs along the fractured surfaces and using them as inputs for the Griffith model, and (iii) relating the fracture toughness to crack propagation initiation. The cracks in all the pristine GBs evolved in a brittle fashion, occasionally forming facetted cleavage planes. Upon introduction of impurities, other mechanisms such as void formation and crack-tip transformation were also observed. Depending on the GB proximity of the occupied segregation sites, local strengthening was seen occasionally for individual CZVEs and at the crack-tip, which was triggered by local impurity-induced crack deflection onto planes with higher cohesion. But when the fracture toughness from the averaged energy release rate was considered, an overall reduction with increasing impurity segregation was found, although to a varying degree for different GBs. This indicates an overall increased degree of embrittlement with increasing P-segregation at the GBs, which concurs with most experimental results reported in the literature. (Less)
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author
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type
Contribution to journal
publication status
epub
subject
in
Computational Materials Science
volume
244
article number
113194
pages
12 pages
publisher
Elsevier
ISSN
0927-0256
DOI
10.1016/j.commatsci.2024.113194
language
English
LU publication?
yes
id
a456ff5a-80db-420c-8e05-0d1f80ccaf1c
date added to LUP
2024-07-04 20:38:45
date last changed
2024-07-09 14:00:03
@article{a456ff5a-80db-420c-8e05-0d1f80ccaf1c,
  abstract     = {{We investigated the role of phosphorus (P) impurities on the fracture toughness and underlying failure mechanisms by means of classical atomistic modeling for a set of ⟨110⟩ symmetric tilt tungsten grain boundaries (GBs). This entailed the utilization of a quasi-static mode I displacement-controlled setup with cohesive zone volume elements (CZVEs) to study failure mechanisms and evaluate the fracture toughness of the GB cracks. The fracture toughness was estimated using three approaches: computing (i) the individual and (ii) the average energy release rate of CZVEs along the fractured surfaces and using them as inputs for the Griffith model, and (iii) relating the fracture toughness to crack propagation initiation. The cracks in all the pristine GBs evolved in a brittle fashion, occasionally forming facetted cleavage planes. Upon introduction of impurities, other mechanisms such as void formation and crack-tip transformation were also observed. Depending on the GB proximity of the occupied segregation sites, local strengthening was seen occasionally for individual CZVEs and at the crack-tip, which was triggered by local impurity-induced crack deflection onto planes with higher cohesion. But when the fracture toughness from the averaged energy release rate was considered, an overall reduction with increasing impurity segregation was found, although to a varying degree for different GBs. This indicates an overall increased degree of embrittlement with increasing P-segregation at the GBs, which concurs with most experimental results reported in the literature.}},
  author       = {{Hiremath, Praveenkumar and Melin, Solveig and Olsson, Pär}},
  issn         = {{0927-0256}},
  language     = {{eng}},
  month        = {{07}},
  publisher    = {{Elsevier}},
  series       = {{Computational Materials Science}},
  title        = {{Phosphorus driven embrittlement and atomistic crack behavior in tungsten grain boundaries}},
  url          = {{http://dx.doi.org/10.1016/j.commatsci.2024.113194}},
  doi          = {{10.1016/j.commatsci.2024.113194}},
  volume       = {{244}},
  year         = {{2024}},
}