Journal ArticleDOI
Ab initio study of helium in α-Fe : Dissolution, migration, and clustering with vacancies
Chu-Chun Fu,Francois Willaime +1 more
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TLDR
In this paper, density functional theory calculations have been performed to study the dissolution and migration of helium in ''ensuremath{\alpha}$-iron, and the stability of small helium-vacancy clusters ${\mathrm{He}}n}{V}_{m}$ ($n,$m=0$ to 4).Abstract:
Density functional theory calculations have been performed to study the dissolution and migration of helium in $\ensuremath{\alpha}$-iron, and the stability of small helium-vacancy clusters ${\mathrm{He}}_{n}{V}_{m}$ ($n$,$m=0$ to 4). Substitutional and interstitial configurations of helium are found to have similar stabilities. The tetrahedral configuration is more stable than the octahedral by 0.2 eV. Interstitial helium atoms are predicted to have attractive interactions and a very low migration energy (0.06 eV), suggesting that He bubbles can form at low temperatures in initially vacancy-free lattices. The migration of substitutional helium by the vacancy mechanism is governed by the migration of the ${\mathrm{HeV}}_{2}$ complex, with an energy barrier of 1.1 eV. The activation energies for helium diffusion by the dissociation and vacancy mechanisms are estimated for the limiting cases of thermal-vacancy regime and of high supersaturation of vacancies. The trends of the binding energies of vacancy and helium to helium-vacancy clusters are discussed in terms of providing additional knowledge on the behavior of He in irradiated iron, necessary for the interpretation of complex experimental data such as thermal He desorption spectra.read more
Citations
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Journal ArticleDOI
Migration energy of He in W revisited by ab initio calculations.
TL;DR: The calculated migration energy of He is very low, around 0.06 eV, which indicates that He atoms can be trapped by other He atoms and can explain the formation of He blisters close to the surface of He implanted tungsten.
Journal ArticleDOI
An integrated model for materials in a fusion power plant: transmutation, gas production, and helium embrittlement under neutron irradiation
TL;DR: In this paper, the authors integrated several different computational techniques to produce a comprehensive picture of the response of materials to neutron irradiation, enabling the assessment of structural integrity of components in a fusion power plant.
Journal ArticleDOI
Ab initio calculations about intrinsic point defects and He in W
TL;DR: In this article, the authors used ab initio calculations in the framework of density functional theory to determine the properties of the self-interstitial atom, the vacancy, vacancy clusters and He in tungsten.
Journal ArticleDOI
Cu-precipitation kinetics in α − Fe from atomistic simulations: Vacancy-trapping effects and Cu-cluster mobility
Frédéric Soisson,Chu-Chun Fu +1 more
TL;DR: In this article, Monte Carlo simulations of the first stages of the coherent precipitation of copper in Fe-Fe alloys are presented, based on a vacancy mediated diffusion model, which takes into account the dependence of vacancy concentrations and migration barriers on the local atomic environment.
Journal ArticleDOI
Microstructural evolution of irradiated tungsten: Ab initio parameterisation of an OKMC model
TL;DR: In this paper, an object kinetic Monte Carlo code has been parameterized on ab initio calculations to model the behaviour of helium atoms implanted in tungsten, in the presence or not of the point defects created during the implantation.
References
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Journal ArticleDOI
Helium accumulation in metals during irradiation – where do we stand?
H. Trinkaus,B.N Singh +1 more
TL;DR: In this paper, the basic ideas pertinent to modelling helium accumulation in metals are reviewed and possible effects of bubble formation on mechanical properties are briefly addressed: hardening and embrittlement, particularly at high temperature where intergranular fracture is induced by the transformation of bubbles to voids at grain boundaries.
Journal ArticleDOI
Multiscale modelling of defect kinetics in irradiated iron
TL;DR: In this article, the authors combine ab initio and kinetic Monte Carlo methods to reproduce the abrupt resistivity changes observed upon annealing at increasing temperatures after electron irradiation in α-iron.
Journal ArticleDOI
Diffusion of interstitial hydrogen into and through bcc Fe from first principles
De-en Jiang,Emily A. Carter +1 more
TL;DR: In this article, periodic spin-polarized density functional theory (DFT) predictions of hydrogen adsorption, absorption, dissolution, and diffusion energetics on and in ferromagnetic (FM) body-centered cubic (bcc) iron are reported.
Journal ArticleDOI
Stability and Mobility of Mono- and Di-Interstitials in α-Fe
TL;DR: The <110> dumbbell is confirmed to be the most stable SIA configuration, 0.7 eV below the <111 > dumbbell, and the lowest-energy migration path corresponds to a nearest-neighbor translation-rotation jump with a barrier of 0.34 eV.
Journal ArticleDOI
Ab initio calculations of defects in Fe and dilute Fe-Cu alloys
TL;DR: In this paper, the binding energies of various Cu containing defects believed to play an important role in the embrittlement of pressure vessel steels under radiation are calculated and discussed, and convergence of the results with the simulated system size is examined.
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