He diffusion in irradiated<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>α</mml:mi><mml:mtext>−</mml:mtext><mml:mi mathvariant="normal">Fe</mml:mi></mml:mrow></mml:math>: An<i>ab-initio</i>-based rate theory model

Ortiz, C.J.; Caturla, M.J.; Fu, Chu‐Chun; Willaime, F.

doi:10.1103/physrevb.75.100102

Cited by 106 publications

(69 citation statements)

References 22 publications

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“…Experimental evidence in bcc Fe 1,2 has also shown that C can act as a vacancy trap through the formation of small, stable V m C n clusters, which has been confirmed in a number of DFT studies. 31,[35][36][37][38] Small V m N n clusters have also been shown to exhibit similar stability. 35 In this section we present the results of a large number of DFT calculations to find the most stable V m X n clusters, where X is He, C, or N, in afmD and afmI Fe.…”

Section: B Vacancy-solute Clusteringmentioning

confidence: 94%

“…4,19,[21][22][23][24][25][26][27][28][29][30] This database of He kinetics and interactions is essential for the interpretation of complex experimental results, such as those present in thermal He desorption spectra. A case in point is the work of Ortiz et al, 31 who have developed a rate theory model based on DFT calculations of the kinetics and interactions of point defects, He and C in bcc Fe (Refs. 25,31, and 33) The model successfully reproduces and interprets the existing experimental desorption results.…”

Section: Introductionmentioning

confidence: 99%

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First-principles study of helium, carbon, and nitrogen in austenite, dilute austenitic iron alloys, and nickel

et al. 2013

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An extensive set of first-principles density functional theory calculations have been performed to study the behavior of He, C, and N solutes in austenite, dilute Fe-Cr-Ni austenitic alloys, and Ni in order to investigate their influence on the microstructural evolution of austenitic steel alloys under irradiation. The results show that austenite behaves much like other face-centered cubic metals and like Ni in particular. Strong similarities were also observed between austenite and ferrite. We find that interstitial He is most stable in the tetrahedral site and migrates with a low barrier energy of between 0.1 and 0.2 eV. It binds strongly into clusters as well as overcoordinated lattice defects and forms highly stable He-vacancy (V m He n ) clusters. Interstitial He clusters of sufficient size were shown to be unstable to self-interstitial emission and VHe n cluster formation. The binding of additional He and V to existing V m He n clusters increases with cluster size, leading to unbounded growth and He bubble formation. Clusters with n/m around 1.3 were found to be most stable with a dissociation energy of 2.8 eV for He and V release. Substitutional He migrates via the dissociative mechanism in a thermal vacancy population but can migrate via the vacancy mechanism in irradiated environments as a stable V 2 He complex. Both C and N are most stable octahedrally and exhibit migration energies in the range from 1.3 to 1.6 eV. Interactions between pairs of these solutes are either repulsive or negligible. A vacancy can stably bind up to two C or N atoms with binding energies per solute atom up to 0.4 eV for C and up to 0.6 eV for N. Calculations in Ni, however, show that this may not result in vacancy trapping as VC and VN complexes can migrate cooperatively with barrier energies comparable to the isolated vacancy. This should also lead to enhanced C and N mobility in irradiated materials and may result in solute segregation to defect sinks. Binding to larger vacancy clusters is most stable near their surface and increases with cluster size. A binding energy of 0.1 eV was observed for both C and N to a [001] self-interstitial dumbbell and is likely to increase with cluster size. On this basis, we would expect that, once mobile, Cottrell atmospheres of C and N will develop around dislocations and grain boundaries in austenitic steel alloys.

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Section: B Vacancy-solute Clusteringmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

First-principles study of helium, carbon, and nitrogen in austenite, dilute austenitic iron alloys, and nickel

et al. 2013

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“…Ascertaining the reactions that occur and quantifying their energetics are important for a fundamental understanding of how point defects, impurities, substitutional atoms, and helium atoms interact in the single crystal lattice of a-Fe. Furthermore, this information is useful for models that explore the kinetics of He diffusion, trapping (clustering), and detrapping (emission), such as rate theory models, [32][33][34][35] kinetic Monte Carlo models, 36,37 and/or phase field models. 38,39 The grain boundary itself and its atomic configuration within these alloy systems plays a significant role in trapping point defects and various atomic species.…”

Section: Introductionmentioning

confidence: 99%

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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“…Let's just underline that the MFRT theory and coarse-grained (OKMC and EKMC) KMC methods ignore partially or totally the crystal lattice and rely on the same set of parameters: point defect diffusivity coefficients; binding energies of point defect with clusters and capture radii, which can be obtained from ab-initio calculations and MD simulations or specific experiments such as isochronal annealing following electron irradiation experiments as in Reference 288 or He desorption experiments. [289,290] These techniques are thus complementary. They are also potential benchmarks of each others.…”

Section: Kmc and Mfrt: Evolution Of The Primary Damagementioning

confidence: 99%

Modeling Microstructure and Irradiation Effects

Becquart

Domain

2010

Metall Mater Trans A

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This article gives an overview of the strategy followed nowadays to model the evolution of metallic alloy microstructures under irradiation. For this purpose, multiscale approaches are very often used, which rely on modeling techniques appropriate to each time and space scale. The main methods used are ab-initio calculations, classical molecular dynamics (MD), kinetic Monte Carlo (KMC), mean field rate theory (MFRT), and dislocation dynamics (DD). These methods are briefly presented along with some of their typical uses and main drawbacks. Some examples are provided of the typical information obtained with each of the techniques.

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He diffusion in irradiatedα−Fe: Anab-initio-based rate theory model

Cited by 106 publications

References 22 publications

First-principles study of helium, carbon, and nitrogen in austenite, dilute austenitic iron alloys, and nickel

First-principles study of helium, carbon, and nitrogen in austenite, dilute austenitic iron alloys, and nickel

Binding of HenV clusters to α-Fe grain boundaries

Modeling Microstructure and Irradiation Effects

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