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Grain boundary embrittlement due to phosphorus in tungsten : An atomistic approach

Hiremath, Praveenkumar LU (2024)
Abstract
Tungsten (W) and its alloys exhibit impressive properties for use in structural components of nuclear fusion reactors. However, impurity induced embrittlement of W grain boundaries (GBs) is a major concern for reactor applications, and necessitates the investigation of the impact of the impurities on the fracture behaviour of the GBs. This work comprises four papers (I-IV) that deal with atomistic modelling of the impact of phosphorus (P) impurities, which is one of the prime embrittlers in W, on the GB cohesion.

The atomistic modelling is performed based on linear elastic fracture mechanics theory. Since interatomic potentials constitute one of the key ingredients for atomistic modelling, a potential that can describe the... (More)
Tungsten (W) and its alloys exhibit impressive properties for use in structural components of nuclear fusion reactors. However, impurity induced embrittlement of W grain boundaries (GBs) is a major concern for reactor applications, and necessitates the investigation of the impact of the impurities on the fracture behaviour of the GBs. This work comprises four papers (I-IV) that deal with atomistic modelling of the impact of phosphorus (P) impurities, which is one of the prime embrittlers in W, on the GB cohesion.

The atomistic modelling is performed based on linear elastic fracture mechanics theory. Since interatomic potentials constitute one of the key ingredients for atomistic modelling, a potential that can describe the fracture of W GBs and the embritteling effect of P impurities is recognized in Papers I and II. In Paper II, the impact of P impurities on the GB strength is evaluated. Papers III and IV are concerned with developing atomistic modelling strategies to address the challenges posed by impurities and extract the fracture toughness and scale-independent interfacial excess potential of cracks in GBs.

The results show that the peak stress required for brittle failure of GBs under uniaxial tensile loading is generally reduced in the presence of P impurities. This suggests that the GBs are weakened by the impurities and that the potential in Paper II can capture P induced GB embrittlement. Likewise, the developed modelling strategies successfully evaluate the fracture toughness and scale-independent interfacial excess potential for pristine and P inhabited GB cracks. A decreasing trend is observed in these fracture quantities with increasing P impurity content, which corroborates the embritteling effect of P impurities on GB fracture.

In summary, the present work provides efficient approaches to investigate the influence of P impurities on the fracture behaviour in tungsten GBs, which are general to a degree that they can be applied to other types of impurities too. Additionally, the herein generated interfacial excess potential data can be used for continuum scale studies of higher-timescale fracture phenomena in P inhabited GBs. (Less)
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author
supervisor
opponent
  • Doc. Profant, Tomás, Brno University of Technology, Czech Republic.
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Tungsten, Phosphorus, Impurities, Molecular statics, Molecular dynamics, Monte Carlo, Fracture mechanics, Grain boundaries, Embrittlement
pages
170 pages
publisher
Department of Mechanical Engineering, Lund University
defense location
Lecture Hall M:E, building M, Klas Anshelms väg 4, Faculty of Engineering LTH, Lund University, Lund.
defense date
2024-09-11 09:00:00
ISBN
978-91-8104-079-1
978-91-8104-078-4
language
English
LU publication?
yes
id
99ba97c0-cfe1-4db4-b750-f1bac41cefd0
date added to LUP
2024-08-05 09:41:59
date last changed
2024-08-16 10:07:18
@phdthesis{99ba97c0-cfe1-4db4-b750-f1bac41cefd0,
  abstract     = {{Tungsten (W) and its alloys exhibit impressive properties for use in structural components of nuclear fusion reactors. However, impurity induced embrittlement of W grain boundaries (GBs) is a major concern for reactor applications, and necessitates the investigation of the impact of the impurities on the fracture behaviour of the GBs. This work comprises four papers (I-IV) that deal with atomistic modelling of the impact of phosphorus (P) impurities, which is one of the prime embrittlers in W, on the GB cohesion.<br/><br/>The atomistic modelling is performed based on linear elastic fracture mechanics theory. Since interatomic potentials constitute one of the key ingredients for atomistic modelling, a potential that can describe the fracture of W GBs and the embritteling effect of P impurities is recognized in Papers I and II. In Paper II, the impact of P impurities on the GB strength is evaluated. Papers III and IV are concerned with developing atomistic modelling strategies to address the challenges posed by impurities and extract the fracture toughness and scale-independent interfacial excess potential of cracks in GBs.<br/><br/>The results show that the peak stress required for brittle failure of GBs under uniaxial tensile loading is generally reduced in the presence of P impurities. This suggests that the GBs are weakened by the impurities and that the potential in Paper II can capture P induced GB embrittlement. Likewise, the developed modelling strategies successfully evaluate the fracture toughness and scale-independent interfacial excess potential for pristine and P inhabited GB cracks. A decreasing trend is observed in these fracture quantities with increasing P impurity content, which corroborates the embritteling effect of P impurities on GB fracture.<br/><br/>In summary, the present work provides efficient approaches to investigate the influence of P impurities on the fracture behaviour in tungsten GBs, which are general to a degree that they can be applied to other types of impurities too. Additionally, the herein generated interfacial excess potential data can be used for continuum scale studies of higher-timescale fracture phenomena in P inhabited GBs.}},
  author       = {{Hiremath, Praveenkumar}},
  isbn         = {{978-91-8104-079-1}},
  keywords     = {{Tungsten; Phosphorus; Impurities; Molecular statics; Molecular dynamics; Monte Carlo; Fracture mechanics; Grain boundaries; Embrittlement}},
  language     = {{eng}},
  month        = {{08}},
  publisher    = {{Department of Mechanical Engineering, Lund University}},
  school       = {{Lund University}},
  title        = {{Grain boundary embrittlement due to phosphorus in tungsten : An atomistic approach}},
  url          = {{https://lup.lub.lu.se/search/files/193352433/Without_articles_Praveenkumar_Hiremath_Dissertation.pdf}},
  year         = {{2024}},
}