Molecular Dynamics Study of Hydrogen in <b><i>α</i></b>-Zirconium

Siripurapu, Ravi Kiran; Szpunar, Barbara; Szpunar, Jerzy A.

doi:10.1155/2014/912369

Cited by 12 publications

(8 citation statements)

References 14 publications

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“…Earlier literature on these measurements [25,84,85] reveals pre-factors ranging from 7.00 × 10 −8 to 4.15 × 10 −7 m·s −1 and migration energies between 0.3 and 0.5 eV, all in a similar temperature range. More recent experiments and molecular dynamics simulations are also consistent with these values [86,87].…”

Section: H Atom Diffusionsupporting

confidence: 75%

Kinetic Model of Incipient Hydride Formation in Zr Clad under Dynamic Oxide Growth Conditions

Reyes

Shah

et al. 2020

Materials

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The formation of elongated zirconium hydride platelets during corrosion of nuclear fuel clad is linked to its premature failure due to embrittlement and delayed hydride cracking. Despite their importance, however, most existing models of hydride nucleation and growth in Zr alloys are phenomenological and lack sufficient physical detail to become predictive under the variety of conditions found in nuclear reactors during operation. Moreover, most models ignore the dynamic nature of clad oxidation, which requires that hydrogen transport and precipitation be considered in a scenario where the oxide layer is continuously growing at the expense of the metal substrate. In this paper, we perform simulations of hydride formation in Zr clads with a moving oxide/metal boundary using a stochastic kinetic diffusion/reaction model parameterized with state-of-the-art defect and solute energetics. Our model uses the solutions of the hydrogen diffusion problem across an increasingly-coarse oxide layer to define boundary conditions for the kinetic simulations of hydrogen penetration, precipitation, and dissolution in the metal clad. Our method captures the spatial dependence of the problem by discretizing all spatial derivatives using a stochastic finite difference scheme. Our results include hydride number densities and size distributions along the radial coordinate of the clad for the first 1.6 h of evolution, providing a quantitative picture of hydride incipient nucleation and growth under clad service conditions.

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Section: H Atom Diffusionsupporting

confidence: 75%

Kinetic Model of Incipient Hydride Formation in Zr Clad under Dynamic Oxide Growth Conditions

Reyes

Shah

et al. 2020

Materials

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“…It is to note that the hydrogen amount was in each test sufficient to form hydrides. However, we did not observe any hydrides in nonannealed specimens; they likely appeared in a very thin zone close to the interface because of a low hydrogen diffusion coefficient, H D , about 10 -7 to 10 -10 cm 2 /s, according to various researchers [62].…”

Section: Discussionmentioning

confidence: 45%

Hydrogen degradation of pre-oxidized zirconium alloys

Szoka

Gajowiec

Zieliński

et al. 2017

Advances in Materials Science

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The presence of the oxide layers on Zr alloys may retard or enhance the hydrogen entry and material degradation, depending on the layer features. This research has been aimed to determine the effects of preoxidation of the Zircaloy-2 alloy at a different temperature on hydrogen degradation. The specimens were oxidised in laboratory air at 350ºC, 700ºC, and 900ºC. After, some samples were tensed at 10-5 strain rate and simultaneously charged with hydrogen under constant direct voltage in 1 N sulfuric acid at room temperature. Other specimens were charged without any tension, then annealed at 400ºC for 4 h and finally tensed at above strain rate. The SEM examinations were performed on the cross-sections and fracture faces of specimens. The obtained results demonstrate the effects of the oxide layer on the cathodic current and hydrogen entry, mechanical properties and the appearance of hydrides and fracture behaviour.

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“…The indenter was operated in the continuous stiffness. The applied load was 5 mN, a Poisson coefficient of 0.3 [ 52 ] and 0.25 [ 53 ] for Zr and ZrN, respectively, were used and an acquisition rate of 10 Hz. The charge to be applied to the indenter has been optimized so as to remain within the range of validity of the hardness measurement, that is to say not exceeding 10% of film thickness for the depth of indentation in order to avoid the influence of the substrate.…”

Section: Methodsmentioning

confidence: 99%

Effects of Nitrogen Content on the Structural, Mechanical, and Corrosion Properties of ZrN Thin Films Grown on AISI 316L by Radiofrequency Magnetron Sputtering

Azibi

Saoula

Madaoui

et al. 2021

Crystal Research and Technology

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Zirconium nitride films are deposited onto stainless steel AISI 316L and silicon (100) by radio frequency magnetron sputtering at different nitrogen flow ratios [N2/(Ar+N2)] varied between 0 and 0.25). Scanning electron microscope, atomic force microscopy, X‐ray diffraction (XRD), and Raman are used to investigate the surface morphology and microstructure of the thin films. The mechanical and electrochemical properties of all coatings are evaluated and compared with the uncoated AISI 316L to explore the efficiency of surface modification. The XRD and Raman analysis show that all the films are crystalline. This shows that the increased nitrogen content leads to a transformation from hexagonal α‐Zr phase to cubic c‐Zr and then to mixed α‐Zr and face centered cubic c‐ZrN phases. The films deposited with nitrogen flow ratio of 0.2 show the highest hardness of 32.2 GPa. Using the potentiodynamic polarization method, the corrosion behavior of the films is studied in Hank's solution. The comparison between uncoated and coated substrates shows a decrease in corrosion current density for all coated samples.

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Molecular Dynamics Study of Hydrogen in α-Zirconium

Cited by 12 publications

References 14 publications

Kinetic Model of Incipient Hydride Formation in Zr Clad under Dynamic Oxide Growth Conditions

Kinetic Model of Incipient Hydride Formation in Zr Clad under Dynamic Oxide Growth Conditions

Hydrogen degradation of pre-oxidized zirconium alloys

Effects of Nitrogen Content on the Structural, Mechanical, and Corrosion Properties of ZrN Thin Films Grown on AISI 316L by Radiofrequency Magnetron Sputtering

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