The effect of hydrogen on the recombination of Frenkel pair in tungsten: A theoretical insight

Qin, Shi-Yao; Jin, Shuo; Niu, Lei; Hao, Jiannan; Zhou, Hongbo; Lü, Guang-Hong

doi:10.1007/s11433-017-9015-0

Cited by 9 publications

(5 citation statements)

References 14 publications

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“…The formation energy of the monovacancy under strain

can be expressed as

where

is the total energy of the strained system containing N W atoms and

vacancies. According to our calculations, the vacancy formation energy in strain-free W is 3.11 eV, consistent with the previous studies [ 24 , 51 , 52 ]. Figure 1 shows the formation energy of a monovacancy in strained W. Under both hydrostatic and biaxial strain, the formation energy of a monovacancy increases with the increasing of tensile strain, while it decreases with the increasing of compressive strain.…”

Section: Resultssupporting

confidence: 92%

Strain Dependence of Energetics and Kinetics of Vacancy in Tungsten

Ren

et al. 2020

Materials

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We investigate the influence of hydrostatic/biaxial strain on the formation, migration, and clustering of vacancy in tungsten (W) using a first-principles method, and show that the vacancy behaviors are strongly dependent on the strain. Both a monovacancy formation energy and a divacancy binding energy decrease with the increasing of compressive hydrostatic/biaxial strain, but increase with the increasing of tensile strain. Specifically, the binding energy of divacancy changes from negative to positive when the hydrostatic (biaxial) tensile strain is larger than 1.5% (2%). These results indicate that the compressive strain will facilitate the formation of monovacancy in W, while the tensile strain will enhance the attraction between vacancies. This can be attributed to the redistribution of electronic states of W atoms surrounding vacancy. Furthermore, although the migration energy of the monovacancy also exhibits a monotonic linear dependence on the hydrostatic strain, it shows a parabola with an opening down under the biaxial strain. Namely, the vacancy mobility will always be promoted by biaxial strain in W, almost independent of the sign of strain. Such unexpected anisotropic strain-enhanced vacancy mobility originates from the Poisson effect. On the basis of the first-principles results, the nucleation of vacancy clusters in strained W is further determined with the object kinetic Monte Carlo simulations. It is found that the formation time of tri-vacancy decrease significantly with the increasing of tensile strain, while the vacancy clusters are not observed in compressively strained W, indicating that the tensile strain can enhance the formation of voids. Our results provide a good reference for understanding the vacancy behaviors in W.

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“…The formation energy of the monovacancy under strain

can be expressed as

where

is the total energy of the strained system containing N W atoms and

Section: Resultssupporting

confidence: 92%

Strain Dependence of Energetics and Kinetics of Vacancy in Tungsten

Ren

et al. 2020

Materials

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“…rhenium (Re) and osmium (Os) are all produced under the real irradiation conditions. These elements can significantly affect the microstructure evolution of defects and complicate the defect-GB interaction processes/mechanisms described here [46][47][48][49][50][51][52][53][54][55]. First-principles calculations by Zhou et al [46] suggest that it is energetically and kinetically favorable for the W GB of Σ5(3 1 0)/[0 0 1] to trap H coming from the bulk.…”

Section: Effects Of the H/he And Alloying Elements On The Healing Promentioning

confidence: 96%

“…The H-GB binding energy is as much as 1.11 eV, while the migration barrier of 0.13-0.16 eV is very low near the GB. In addition, H could also bind with the bulk SIA n prior to its segregation to the GB with the SIA-H binding energy (~ 0.43 eV [47]) as the energetic driving force. Consequently, the segregation of the SIA n may be suppressed to a certain extent by H, which may enhance the annihilation of bulk SIA n -V. H/He also prefers to bind with the V and small V n to form stable complexes [48], which may hinder the segregation of the V. Furthermore, the interplay among the SIA n and H/He as well as the V within the GB can inevitably affect the healing efficiency of the mechanism reviewed in the present paper.…”

Section: Effects Of the H/he And Alloying Elements On The Healing Promentioning

confidence: 99%

Interaction of radiation-induced defects with tungsten grain boundaries at across scales: a short review

Zhang

et al. 2020

Tungsten

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As promising candidates for plasma-facing materials, tungsten-based materials suffer the irradiation of high-energy neutrons in addition to the hydrogen isotopes and helium irradiation and the high-thermal flux. Radiation-produced defects, e.g. selfinterstitial atoms (SIAs) and vacancies (Vs), can induce the hardening and embrittlement of tungsten, meanwhile enhancing the retention of hydrogen isotopes and helium in tungsten. Reducing the grain size of materials to introduce a high density of defect sinks, e.g., grain boundaries (GBs) prevalent in nano-/ultrafine-crystalline materials, was demonstrated to be an effective approach for mitigating irradiation damage in tungsten. In this paper, we reviewed the theoretical advances in exploring radiation-resistance of nano-structured tungsten at across scales. It was concentrated on the results of molecular dynamics, molecular statics, and the object kinetic Monte Carlo simulations on the fundamental interaction of the radiationcreated Vs and SIAs with the GB. These mechanisms include GB-promoted V/SIA migration and SIA-V recombination, interstitial-emission induced annihilation, coupling of the V migration close to the GB with the SIA motion within the GB, and interstitial reflection by the locally dense GB structure. We proposed the remaining scientific issues on the defect-GB interactions at across scales and their relation to experimental observations. We prospected the possible trends for simulating the radiation damage accumulation and healing processes in nano-structured tungsten in terms of the development of the across-scale computational techniques and efficiency of the GB-enhanced tolerance of tungsten to irradiation under complex in-service conditions.

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“…H and He also induced pronounced synergistic effects in the samples under triple ion irradiation. Previous studies have reported the inhibition of vacancies-interstitials recombination by He [32] and H [33] alone. During triple ion irradiation, H, He, and displacement cascades induced by heavy ions coexist in a relatively small region.…”

Section: Discussionmentioning

confidence: 98%

Effect of Damage Rate on the Cavity Swelling of Pure Nickel Irradiated with Triple Ion Beams

Huang

Gao

Liu

et al. 2022

Metals

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He-H synergistic effects influence the performance of structural materials in fusion reactors. Due to the lack of high-intensity fusion neutron sources, multiple ion beam irradiation has been widely used as an emulation method to study its synergistic effects. However, the damage rate under multiple ion beam irradiation is three to four orders of magnitude higher than that under fusion neutron irradiation, and its effect on the cavity swelling is still unclear. In this study, pure nickel was irradiated with single and triple ion beams to ~1 displacements per atom (dpa) at 450 °C. The damage rate ranged from 1.4 × 10−4 to 1.4 × 10−3 dpa/s, with the identical gas-dose ratios of ~400 H appm/dpa and 100 He appm/dpa. Large and isolated cavities formed under single ion irradiation, while triple ion irradiation induced smaller and denser cavities and higher swelling. As the damage rate increased, the cavity size, density, and swelling decreased, due to the constraint of cavity nucleation and growth processes. The effect of damage rate on cavity evolution under triple ion irradiation strongly depends on two competing factors: the enhancement of aggregation and binding of H/He/vacancies, and the enhancement of vacancies–interstitials recombination with increasing damage rate.

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The effect of hydrogen on the recombination of Frenkel pair in tungsten: A theoretical insight

Cited by 9 publications

References 14 publications

Strain Dependence of Energetics and Kinetics of Vacancy in Tungsten

Strain Dependence of Energetics and Kinetics of Vacancy in Tungsten

Interaction of radiation-induced defects with tungsten grain boundaries at across scales: a short review

Effect of Damage Rate on the Cavity Swelling of Pure Nickel Irradiated with Triple Ion Beams

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