On the sipa contribution to radiation creep

Nichols, F.A.

doi:10.1016/0022-3115(79)90164-8

Cited by 21 publications

(4 citation statements)

References 23 publications

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“…at not too low temperature. In this regime the only dependency comes from the dependency of the bias factors on dislocation density, which is usually considered as logarithmic and is therefore small (Nichols, 1979). We note that similar creep rates during stage II in CW and SA materials are not a definite argument in favour of SIPA models, since microstructures of SA and CW tend to become similar as the dose increases.…”

Section: Dependency On Dislocation Densitymentioning

confidence: 86%

“…Other studies have shown that creep strain rates predicted by SIPA-I were far too low (Nichols, 1979) (Simonen & Hendrick, 1979) (Kishimoto, et al, 1988). The difficulty, while assessing the magnitude of SIPA-I creep, is to use the correct value for the fraction of freely migrating defects which are the only ones to participate to creep strain in SIPA models (Nichols, 1979), and to use correct values for defect polarizabilities. A recent study based on cluster dynamics confirmed the too low magnitude of SIPA-I effect .…”

Section: Stress Dependency and Magnitudementioning

confidence: 99%

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Irradiation Creep in Materials

Onimus

Jourdan

et al. 2020

Comprehensive Nuclear Materials

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Section: Dependency On Dislocation Densitymentioning

confidence: 86%

Section: Stress Dependency and Magnitudementioning

confidence: 99%

Irradiation Creep in Materials

Onimus

Jourdan

et al. 2020

Comprehensive Nuclear Materials

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“…By inserting the concentration profiles given by (18) into (24) and performing the corresponding derivatives and integrals, the following result is obtained for the strength: The sink strengths derived by Woo and Gosele [16] for the boundary conditions (2b), with the concentration profiles being given by (20), can also be written as (25). I n this case a simpler form is derived for q(qi, q,), namely ' From the definition of qi and q,, (14), and (15) it is evident that, independently of the boundary conditions under considoration, the hollow cylinder sink strengths given by (26) The hollow cylinder sink strengths given by (25) t o (27) are plotted in Fig. 2 for each set of boundary conditions and using parametric values of /?.…”

Section: Dislocation Sink Strengthmentioning

confidence: 99%

Stress Induced Anisotropic Diffusion of Intrinsic Point Defects towards Dislocations in H.C.P. Crystals

Grande

Savino

Tomé

1987

Physica Status Solidi (b)

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Dedicated to Prof. Dr. A. SEEGEB on the occasion of his 60th birthdayThe diffusion equations for vacancies and interstitials in the field of straight edge dislocations are numerically solved for a crystal under irradiation and uniaxially stress. The main dislocation systems in hexagonal closed packed metals are considered. The diffusion model takes into account the full lattice and defect symmetry in the equilibrium and migration configurations. A diffusivity tensor for strained h a p . metals is deduced, which depends linearly on the strain field. This tensor allows to solve analytically the steady state defect flux towards a hollow cylinder in a homogeneously strained crystal. The resulting vacancy and interstitial absorption (sink strength) are calculated and compared with the ones obtained numerically when the dislocation field is taken into account. It is shown that both approaches result in a similar dependence of the sink strengths on the homogeneous strain as far as a correct capture radius is adopted for the hollow cylinder. The dependence of the results on the boundary conditions and the defect symmetry considered is discussed. For the numerical calculations defect symmetries consistent with those calculated for magnesium are used.Die Diffusionsgleichungen fur Leerstellen und Zwischengitteratomen im Feld von geraden Stufenversetzungen werden numerisch fur einen Kristall unter Bestrahlung und fur uniaxiale Spannung gelost. Die Hauptversetzungssysteme in hexagonal dichtest gepackten Metallen werden betrachtet. Das Diffusionsmodell beriicksichtigt die vollstandige Gitter-und Defektsymmetrie in den Gleichgewichts und den Bewegungskonfigurationen. Ein Diffusionstensor fur verzerrte h.d.p.-Metalle wird abgeleitet, der linear von dem Verzerrungsfeld abhangt. Dieser Tensor gestattet, den stationiiren StorstellenfluB zu einem Hohlzylinder in einem homogen verzerrten Kristall analytisch zu berechnen. Die resultierende Leerstellen-und Zwischengitteratom absorption (Senkenstiirke) werden berechnet und mit denen verglichen, die numerisch unter Beriicksichtigung des Versetzungsfeldes erhalten werden. Es wird gezeigt, daB beide Verfahren zu einer Lhnlichen Abhiingigkeit der Senkenstarke von der homogenen Verzerrung fuhren, falls korrekte Einfangradien fur den Hohlzylinder angenommen werden. Die Abhiingigkeit der Ergebnisse von den Randbedingungen und der betrachteten Defektsymmetrie wird diskutiert. Fur die numerisohen Berechnungen werden Defektsymmetrien benutzt, die konsistent mit den fur Magnesium berechneten sind.

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“…5 °C) at 1300 oc (19). The 0/U ratios of samples [7][8][9][10][11][12][13][14] (molybdenum encapsulated) and [9][10][11][12] (ttmgsten encapsulated) were 1. 996 and 1.…”

Section: B Isothermal Sihteringmentioning

confidence: 99%

Behavior of Metallic Inclusions in Uranium Dioxide

Yang

Olander

1981

Nuclear Technology

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Tne mobility of micron-size powders of refractory and noble metals in uo 2 1vas investigated under isothermal and temperature gTadient conditions, The metal particles were initially placed between two polished surfaces of uo 2 and any movement which occurred during high temperature annealing was determined microscopically, Tungsten and molybdenum particles 1 to 10 pm in diameter were immobile in uo 2 at 2500°C in a temperature gradient of 1400°C/cm. Ruthenium, however, dissolved into and spread through hypostoichiometric, polycrystalline urania and was found after isothermal annealing as the U-Ru intennetallic compotmd in the grain boundaries of t11e oxi(lc, 111e mechanism does not involve bodily motion of the metal particles. Rather, ruthenium dissolves 1n the grain bmmdaries of the oxide, migrates as atoms via the same pathway, and reacts while migrating to fonn URu 3 , This pToduct g r·m-vs as layers in th; grain boundaries, Isothennal n1thenium spreading follmJcd silnple diffu:;ion theory, and appaTent solubilities and effective di±fusivitics were obtained from the data for the temperature nmge 2000 to 2300°C. In a temperature gradient, ruthenium moves to the hot zones of 00 2 ; the mcchonism appears to be the same as found for isothermal spreading, but th; extent of movement up the temperature gradient cannot be c:x:plained by simple diffusion theory, even with an appreciable Soret effect.

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On the sipa contribution to radiation creep

Cited by 21 publications

References 23 publications

Irradiation Creep in Materials

Irradiation Creep in Materials

Stress Induced Anisotropic Diffusion of Intrinsic Point Defects towards Dislocations in H.C.P. Crystals

Behavior of Metallic Inclusions in Uranium Dioxide

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