Oxidation and hydrogen uptake in zirconium, Zircaloy-2 and Zircaloy-4: Computational thermodynamics and ab initio calculations

Glazoff, Michael V.; Tokuhiro, Akira; Rashkeev, Sergey N.; Sabharwall, Piyush

doi:10.1016/j.jnucmat.2013.09.038

Cited by 41 publications

(17 citation statements)

References 65 publications

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“…2(b). In α-Zr, H atoms prefer to occupy the tetrahedron sites as predicted by previous DFT calculations [29,30,34] with rare exceptions [35]. The simulation cell contained 2048 Zr atoms, with the number of H atoms varying from 1 to 2048 to represent various compositions.…”

Section: Hydrogen Solution Energymentioning

confidence: 88%

Homogeneous hydride formation path in α-Zr: Molecular dynamics simulations with the charge-optimized many-body potential

Zhang

Bai

et al. 2016

Acta Materialia

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Section: Hydrogen Solution Energymentioning

confidence: 88%

Homogeneous hydride formation path in α-Zr: Molecular dynamics simulations with the charge-optimized many-body potential

Zhang

Bai

et al. 2016

Acta Materialia

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“…In this system in particular, it has been found that H preferentially occupies tetrahedral sites in the Zr lattice, rather than other sites 15,21,22 . Some works have focused on the octahedral site as the main location for H atom solution, however such works appear to be in the minority 23,24 . It has been theoretically predicted that the FCT structure of ZrH 2 can have another stable phase for c/a ¿ 1 25,36 .…”

Section: Introductionmentioning

confidence: 99%

The thermodynamics of hydride precipitation: The importance of entropy, enthalpy and disorder

et al. 2014

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The thermodynamics of H/α-Zr solid solution and zirconium hydride phases were studied using density functional theory. Disorder in ζ, γ and δ hydrides and solid solutions were modelled using a statistically significant number of randomly generated structures in combination with special quasirandom structures and solid solutions with a range of concentrations. This is used in conjunction with a calculation of thermodynamic parameters of the system, including the temperature dependent sensible enthalpy, configurational entropy and vibrational entropy of the different crystals in the system, developed from phonon density of states. It was found that precipitation of hydrides is not thermodynamically favourable for Zr-H solid solutions containing less than 300 ppm H, suggesting that a mechanism must cause local concentration of H atoms to a greater amount than found globally in experimental samples containing hydrides. Temperature drives the reaction in the direction of solution, primarily due to entropic effects. Generally, γ hydride is the most stable phase, although it is very close in energy to the δ-phase. The sensible enthalpy of precipitation assists in stabilising HCP hydrides, and the configurational entropy change during precipitation favours FCC hydrides. None of the thermodynamic contributions are found to be negligible in driving precipitation.arXiv:1401.5637v1 [cond-mat.mtrl-sci] 22 Jan 2014 2

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“…It means that the trajectory will deviate from a straight line. Secondly, migration barriers for hydrogen between two octahedral interstitials increase when an oxygen atom is present in the neighboring interstitial; migration enthalpy is about 0.6 eV in the absence of oxygen and 0.9 V in its presence [50].…”

Section: Oxides and Hydrogen Entrymentioning

confidence: 99%

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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Oxidation and hydrogen uptake in zirconium, Zircaloy-2 and Zircaloy-4: Computational thermodynamics and ab initio calculations

Cited by 41 publications

References 65 publications

Homogeneous hydride formation path in α-Zr: Molecular dynamics simulations with the charge-optimized many-body potential

Homogeneous hydride formation path in α-Zr: Molecular dynamics simulations with the charge-optimized many-body potential

The thermodynamics of hydride precipitation: The importance of entropy, enthalpy and disorder

Hydrogen degradation of pre-oxidized zirconium alloys

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