In situ XRD analysis of the oxide layers formed by oxidation at 743 K on Zircaloy 4 and Zr–1NbO

Petigny, N.; Barbéris, Pierre; Lemaignan, C.; Valot, C.; Lallemant, M.

doi:10.1016/s0022-3115(00)00051-9

Cited by 149 publications

(90 citation statements)

References 18 publications

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“…These conditions are very similar to those experienced by oxidising zirconium alloys in nuclear reactors or autoclaves, and these oxide films also demonstrate a continuous reduction in tetragonal phase fraction and degradation in the protective character of the oxide layer (Petigny, 2000;P. Platt et al, 2015b;Polatidis et al, 2013;Preuss et al, 2011;Zhang et al, 2010).…”

Section: Introductionmentioning

confidence: 53%

“…As zirconium alloys oxidise entirely due to the inward migration of oxygen ions (Cox, 2005), there should be an increasing concentration of oxygen vacancies approaching the metal-oxide interface from the oxide surface (Cox and Pemsler, 1968;Na Ni et al, 2011;Yoo, 2001). This could be a contributing factor to the increased tetragonal phase fraction close to the metal-oxide interface (Petigny, 2000).…”

Section: Introductionmentioning

confidence: 99%

“…Zirconia thin films can experience residual biaxial compressive stresses of the order of MPa to GPa, whether the material is applied as a coating (Scardi et al, 2004;Teixeira and Andritschky, 1999), or formed during thermal oxidation (Béchade et al, 2000;Jacquot et al, 1996;Petigny, 2000;P. Platt et al, 2015b;Polatidis et al, 2013;Preuss et al, 2011;Zhang et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Peridynamic simulations of the tetragonal to monoclinic phase transformation in zirconium dioxide

Platt

Mella

DeMaio

et al. 2017

Computational Materials Science

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Whether present as a manufactured stabilised ceramic, or as an oxide layer on zirconium alloys, mechanical degradation in zirconia is influenced by the tetragonal to monoclinic phase transformation.Peridynamic theory was implemented within the Abaqus finite element framework to understand how the tetragonal to monoclinic phase transformation can itself cause fracture in zirconia. In 2D these simulations represent a single grain, transforming via an isometric dilational expansion, surrounded by a homogenous monoclinic oxide. The effect of transformation time, applied bi-axial pressure, and the fracture strain were assessed using the change in strain energy and the amount of damage in the oxide surrounding the transformed grain. Reducing the applied compressive stress or applying a tensile stress reduces the transformation strain energy. The introduction of a fracture strain leads to damage in the surrounding oxide region largely in the form of cracks, and reduces the transformation strain energy further by reducing the constraint on the transforming grain. The extent of the fracture, and reduction in constraint on the transformed grain, is more significant with the application of a biaxial tensile pressure.

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Section: Introductionmentioning

confidence: 53%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Peridynamic simulations of the tetragonal to monoclinic phase transformation in zirconium dioxide

Platt

Mella

DeMaio

et al. 2017

Computational Materials Science

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“…These stresses are mainly stemming from the change of the molar volume between the metal and the oxide which is characterized by the Pilling and Bedworth ratio (PBR). Since the PBR is about 1.5 for the Zr/ZrO 2 system, this induces high compressive stresses (around -1.5 GPa) [3,4] parallel to the metal/oxide interface. They could explain the presence of tetragonal zirconia (ZrO2t) at the interface, which transforms in monoclinic zirconia (ZrO2m) as oxide thickens [2,4,5].…”

Section: Introductionmentioning

confidence: 99%

Microstresses in ZrO<sub>2</sub> Layer and Lateral Cracking

Berdin

Tang

Pascal

2014

AMR

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Abstract. Micromechanical simulations of polycrystalline zirconia using the finite element method are performed in order to obtain the stresses at the grain scale of a zirconium oxide layer, since these microstresses are important for damage prediction of the layer and then oxidation kinetics. The crystallographic texture of the layer of monoclinic zirconia is taken into account. The results show that even under high compressive macroscopic stresses, the microstresses can contribute to lateral cracking promoted by the presence of tetragonal zirconia.

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“…Nevertheless, Nb-containing alloys are oxidised faster than recrystallised Zircaloy in oxygen and in water vapour [4,[8][9][10][11][12], at the beginning of the oxidation, but the kinetic transition is not so sharp in Nb-containing alloys and it occurs after a longer time. In autoclave, different results are obtained, these alloys showing in most cases a better resistance to corrosion [14,15].…”

Section: Introductionmentioning

confidence: 99%

Oxidation kinetics of ZrNbO in steam: Differences between the pre- and post-transition stages

Tupin

Pijolat

Valdivieso

et al. 2005

Journal of Nuclear Materials

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Zirconium based alloys (and particularly Zircaloy-4) are widely used as cladding material of fuel rods in water-cooled nuclear reactors. However, advanced alloys are now used for longer operation time in more severe conditions. One of these new alloys is a ZrNbO, which contains 1% of Nb as alloying element (instead of Sn in the case of Zircaloy-4).This ZrNbO alloy, like many zirconium alloys, undergoes a kinetic transition, which is a sharp increase in the oxidation rate when the oxide thickness exceeds a critical value. In the pre-transition stage, the kinetic oxidation curves are approximately parabolic (which is generally interpreted by a diffusion controlling step), and tend towards a quasi-linear behaviour after the transition. Recent studies have shown that the oxygen pressure has an accelerating effect on the oxidation rate of ZrNbO; a platinum layer deposited on the oxide surface has the same effect, both in oxygen and in water vapour. Thus it has been suggested that the oxidation in the pre-transition stage could be described by a mixed reaction-diffusion kinetics. Due to the lack of consistent data on the effect of water vapour on the oxidation rate of ZrNbO before and after the transition, and to confirm (or not) these interpretations, we have studied the oxidation of ZrNbO by isothermal thermogravimetry at 550°C, under controlled partial pressures of water vapour (13 to 80 hPa) and hydrogen (10 hPa). The aim is to verify if the oxidation proceeds in a steady state and if there is a rate-limiting step in one (or both) stages, and to clearly evidence the differences between the pre-and post transition stages from the kinetic point of view.TG-DSC experiments have shown that the system is in a steady state from the beginning of the oxidation, in the pre-and post-transition stages. Then, the existence of a ratelimiting step was verified using an experimental method based on temperature or pressure jumps: it has been concluded that this assumption is valid in both stages, which is not compatible with the assumption of a mixed reaction-diffusion controlled rate). Moreover, it comes out that the kinetic behaviour is different before and after the transition: the influence of temperature jumps is greater in pre-transition, whereas the effect of water vapour partial pressure is more pronounced in post-transition (nevertheless, an accelerating effect is also observed before the transition). No influence of hydrogen partial pressure has been observed. Besides, the higher the Nb content in the alloy, the higher the oxidation rate (in pre-transition). A mechanism has been proposed to account for the results obtained in pretransition, involving the diffusion of adsorbed species in the porous part of the oxide layer as rate-determining step.Keywords: ZrNbO ; oxidation ; kinetics ; water vapour ; steady state ; rate-limiting step. 1 IntroductionDespite numerous works dedicated to the oxidation kinetics of zirconium alloys by pressurized water, water vapour or oxygen, the mechanisms and the rate-limiting steps...

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In situ XRD analysis of the oxide layers formed by oxidation at 743 K on Zircaloy 4 and Zr–1NbO

Cited by 149 publications

References 18 publications

Peridynamic simulations of the tetragonal to monoclinic phase transformation in zirconium dioxide

Peridynamic simulations of the tetragonal to monoclinic phase transformation in zirconium dioxide

Microstresses in ZrO<sub>2</sub> Layer and Lateral Cracking

Oxidation kinetics of ZrNbO in steam: Differences between the pre- and post-transition stages

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