Trapping of hydrogen and helium at grain boundaries in nickel: An atomistic study

Baskes, M. I.; Vítek, V.

doi:10.1007/bf02663018

Cited by 52 publications

(38 citation statements)

References 31 publications

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“…Kurtz and Heinisch also found that the maximum He binding energy increases linearly with the grain boundary excess free volume, similar to prior work in fcc nickel. 59 In subsequent studies, Gao, Heinisch, and Kurtz 49 found a relationship between the maximum binding energy and grain boundary energy as well. Additionally, Gao et al started to detail the diffusion trajectories of interstitial and substitutional He atoms along a R3 and R11 grain boundary and found that the dimensionality of migration of interstitial He may depend on temperature (e.g., in the R3(112) boundary).…”

Section: Introductionmentioning

confidence: 92%

Binding of HenV clusters to α-Fe grain boundaries

Tschopp

Gao

Solanki³

2014

Journal of Applied Physics

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Articles you may be interested inBinding energetics of substitutional and interstitial helium and di-helium defects with grain boundary structure in - The objective of this research is to explore the formation/binding energetics and length scales associated with the interaction between He n V clusters and grain boundaries in bcc a-Fe. In this work, we calculated formation/binding energies for 1-8 He atoms in a monovacancy at all potential grain boundary (GB) sites within 15 Å of the ten grain boundaries selected (122106 simulations total). The present results provide detailed information about the interaction energies and length scales of 1-8 He atoms with grain boundaries for the structures examined. A number of interesting new findings emerge from the present study. First, the R3(112) "twin" GB has significantly lower binding energies for all He n V clusters than all other boundaries in this study. For all grain boundary sites, the effect of the local environment surrounding each site on the He n V formation and binding energies decreases with an increasing number of He atoms in the He n V cluster. Based on the calculated dataset, we formulated a model to capture the evolution of the formation and binding energy of He n V clusters as a function of distance from the GB center, utilizing only constants related to the maximum binding energy and the length scale. V C 2014 AIP Publishing LLC.

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Section: Introductionmentioning

confidence: 92%

Binding of HenV clusters to α-Fe grain boundaries

Tschopp

Gao

Solanki³

2014

Journal of Applied Physics

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“…An order-of-magnitude estimate of Γ max;i g can be made by considering a square network of possible adsorption sites, spaced 0.5 nm from one another, 8 giving Γ max;i g % 4 10 18 =m 2 % 7 10 À6 mol=m 2 . Based on Eqs.…”

Section: Polyhedral Packing Unitsmentioning

confidence: 99%

“…6 This concept and related models, [7][8][9] however, have not been made sufficiently predictive due to a lack of fundamental understanding of the chemomechanical mechanisms of embrittlement, despite considerable research effort. [10][11][12][13][14][15][16][17][18][19][20][21][22] One challenge towards such an understanding is to establish the mechanistic connections between the mechanochemistry of hydrogen adsorption and the strength reduction of grain boundaries (GBs) with realistic atomic structure and under loading conditions pertinent to applications.…”

Section: Introductionmentioning

confidence: 99%

“…The central hole of a deltahedron contains a large free volume and thus is an energetically favorable interstitial site for trapping the small H atom. 10,31 We develop a computational route to uniquely divide a relaxed GB into deltahedral packing units by using a H atom as a probe. That is, a single H atom is embedded near a GB by assigning its initial position based on the nodal coordinates of a spatial mesh, with uniform nodal spacing of, for example, 0.1 Å.…”

Section: Introductionmentioning

confidence: 99%

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Hydrogen embrittlement of grain boundaries in nickel: an atomistic study

et al. 2017

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The chemomechanical degradation of metals by hydrogen is widely observed, but not clearly understood at the atomic scale. Here we report an atomistic study of hydrogen embrittlement of grain boundaries in nickel. All the possible interstitial hydrogen sites at a given grain boundary are identified by a powerful geometrical approach of division of grain boundary via polyhedral packing units of atoms. Hydrogen segregation energies are calculated at these interstitial sites to feed into the Rice-Wang thermodynamic theory of interfacial embrittlement. The hydrogen embrittlement effects are quantitatively evaluated in terms of the reduction of work of separation for hydrogen-segregated grain boundaries. We study both the fast and slow separation limits corresponding to grain boundary fracture at fixed hydrogen concentration and fixed hydrogen chemical potential, respectively. We further analyze the influences of local electron densities on hydrogen adsorption energies, thereby gaining insights into the physical limits of hydrogen embrittlement of grain boundaries.

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“…This is because the helium born in the material during tritium exposure has clustered into small bubbles as a result of the 400°C off-gassing treatment (helium bubble formation has been shown to occur in austenitic stainless steels upon annealing at 350°C [12]). Helium trapped in even small clusters is very strongly bound (binding energies of 3.5-4.0 eV [13]) and is not free to migrate at any temperature appreciably below the melting point.…”

Section: Discussion Weld Response Hazmentioning

confidence: 99%

Helium-Induced Degradation in the Weldability of an Austenitic Stainless Steel

Lin

Goods

Grossbeck

et al. 1990

Effects of Radiation on Materials: 14th International Symposium (Volume I)

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ABSTRACT:Autogenous gas tungsten arc welding was performed onHe-doped type 316 stainless steel. Helium was uniformly implanted in the material using the "tritium trick" to levels of 27 and 105 appm. Severe intergranular cracking occurred in both fusion and heat-affected zones. Microstructural observations of the fusion zone indicated that the pore size, degree of porosity, and tendency to form cracks increased with increasing helium concentration. Scanning electron microscopy showed that cracking in He-doped materials was due to the precipitation of helium bubbles on grain boundaries and dendrite interfaces.Results of the present study demonstrate that the use of conventional welding techniques to repair materials degraded by exposure to radiation may be difficult if the irradiation results in the generation of even rather small amounts of helium.

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Trapping of hydrogen and helium at grain boundaries in nickel: An atomistic study

Cited by 52 publications

References 31 publications

Binding of HenV clusters to α-Fe grain boundaries

Binding of HenV clusters to α-Fe grain boundaries

Hydrogen embrittlement of grain boundaries in nickel: an atomistic study

Helium-Induced Degradation in the Weldability of an Austenitic Stainless Steel

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