The effect of diffusion anisotropy on dislocation bias and irradiation creep in cubic lattice materials

Borodin, V.A.; Ryazanov, A. I.

doi:10.1016/0022-3115(94)90180-5

Cited by 18 publications

(9 citation statements)

References 22 publications

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“…This analysis therefore shows that, in addition to the classical thermodynamic driving force, reduced migration barriers contribute significantly to sink efficiency and that these reduced barriers are unequivocally due to saddle point anisotropy. The effect of interface elastic fields on defect migration energies is similar to that found in the vicinity of isolated dislocations 46 47 48 49 . However, elastodiffusion near interfaces—including semicoherent ones—is not reducible to elastodiffusion near dislocations because the stress fields of the former are in general composed of two contributions: one arising from infinite arrays of discrete dislocations and the other from coherency stresses.…”

Section: Resultssupporting

confidence: 67%

Non-random walk diffusion enhances the sink strength of semicoherent interfaces

et al. 2016

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Clean, safe and economical nuclear energy requires new materials capable of withstanding severe radiation damage. One strategy of imparting radiation resistance to solids is to incorporate into them a high density of solid-phase interfaces capable of absorbing and annihilating radiation-induced defects. Here we show that elastic interactions between point defects and semicoherent interfaces lead to a marked enhancement in interface sink strength. Our conclusions stem from simulations that integrate first principles, object kinetic Monte Carlo and anisotropic elasticity calculations. Surprisingly, the enhancement in sink strength is not due primarily to increased thermodynamic driving forces, but rather to reduced defect migration barriers, which induce a preferential drift of defects towards interfaces. The sink strength enhancement is highly sensitive to the detailed character of interfacial stresses, suggesting that ‘super-sink' interfaces may be designed by optimizing interface stress fields. Such interfaces may be used to create materials with unprecedented resistance to radiation-induced damage.

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Section: Resultssupporting

confidence: 67%

Non-random walk diffusion enhances the sink strength of semicoherent interfaces

et al. 2016

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“…The increase of the relaxation volume due to the anisotropy at saddle point is such that the effect on the sink strength is rather large. Borodin and Ryazanov did not resort to some of the assumptions made by Skinner and Woo [37] and obtained a few percents decrease of the sink strength for interstitials and an increase of about 20 % for vacancies. More recently, Sivak and Sivak [75] showed with OKMC calculations that the anisotropy of vacancies at saddle point is responsible for complex variations of the sink strength with the dislocation type.…”

Section: Analysis and Discussionmentioning

confidence: 96%

“…Although this effect had been discussed previously [31,32,33], these authors also suggested that the anisotropy of point defects at saddle position could have an effect on the sink strength. Such an effect was later confirmed for straight dislocations [34,35,36,37], infinitesimal dislocation loops [38] and voids [39]. However, all these works contain approximations to make calculations tractable, so the values of sink strengths significantly vary from one study to the other [37].…”

Section: Introductionmentioning

confidence: 93%

“…Such an effect was later confirmed for straight dislocations [34,35,36,37], infinitesimal dislocation loops [38] and voids [39]. However, all these works contain approximations to make calculations tractable, so the values of sink strengths significantly vary from one study to the other [37]. In addition, the elastic dipoles of point defects are based on empirical potential calculations, which are not always in agreement with first-principles calculations.…”

Section: Introductionmentioning

confidence: 99%

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Effect of saddle point anisotropy of point defects on their absorption by dislocations and cavities

et al. 2017

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International audienceDeveloping predictive models for the microstructure evolution of materials requires an accurate description of the point defects fluxes to the different sinks, such as dislocations, grain boundaries and cavities. This work aims at improving the evaluation of sink strengths of dislocations and cavities using object kinetic Monte-Carlo simulations parametrized with density functional theory calculations. The present accurate description of point defects migration enables quantitative assessment of the influence of the point defects anisotropy at saddle point. The results in aluminum show that the anisotropy at saddle point has a large influence on sink strengths. In particular, this anisotropy leads to the cavity being a biased sink. These results are explained by the analysis of the point defect trajectories to the sinks, which are shown to be strongly affected by the saddle point anisotropy

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“…More generally, the strain-induced anisotropy of point defect diffusion should be taken into account in calculating the defect fluxes to sinks like dislocations, cavities etc., as accurate evaluation of the sink absorption efficiency for point defects is critical in determining creep rates 80 . Sinks create an elastic strain field in their vicinity, which will lead to anisotropic diffusion of point defects and therefore a biased flux of point defects to those sinks.…”

Section: Discussionmentioning

confidence: 99%

Impact of homogeneous strain on uranium vacancy diffusion in uranium dioxide

et al. 2015

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We present a detailed mechanism of, and the effect of homogeneous strains on, the migration of uranium vacancies in UO2. Vacancy migration pathways and barriers are identified using density functional theory (DFT) and the effect of uniform strain fields are accounted for using the dipole tensor approach. We report complex migration pathways and non-cubic symmetry associated with the uranium vacancy in UO2 and show that these complexities need to be carefully accounted for to predict the correct diffusion behavior of uranium vacancies. We show that under homogeneous strain fields, only the dipole tensor of the saddle with respect to the minimum is required to correctly predict the change in the energy barrier between the strained and the unstrained case. Diffusivities are computed using kinetic Monte Carlo (KMC) simulations for both neutral and fully charged state of uranium single and di-vacancies. We calculate the effect of strain on migration barriers in the temperature range 800 -1800 K for both vacancy types. Homogeneous strains as small as 2% have a considerable effect on diffusivity of both single and di-vacancies of uranium, with the effect of strain being more pronounced for single vacancies than di-vacancies. In contrast, the response of a given defect to strain is less sensitive to changes in the charge state of the defect. Further, strain leads to anisotropies in the mobility of the vacancy and the degree of anisotropy is very sensitive to the nature of the applied strain field for strain of equal magnitude. Our results suggest that the influence of strain on vacancy diffusivity will be significantly greater when single vacancies dominate the defect structure, such as sintering, while the effects will be much less substantial under irradiation conditions where di-vacancies dominate.

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The effect of diffusion anisotropy on dislocation bias and irradiation creep in cubic lattice materials

Cited by 18 publications

References 22 publications

Non-random walk diffusion enhances the sink strength of semicoherent interfaces

Non-random walk diffusion enhances the sink strength of semicoherent interfaces

Effect of saddle point anisotropy of point defects on their absorption by dislocations and cavities

Impact of homogeneous strain on uranium vacancy diffusion in uranium dioxide

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