The H-Zr (hydrogen-zirconium) system

Zuzek, E.; Abriata, J. P.; San-Martin, A.; Manchester, F. D.

doi:10.1007/bf02843318

Cited by 251 publications

(157 citation statements)

References 68 publications

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“…Experimentally, microstructural characterization of alloy Zr-4 was conducted by Vandersande and Bement [49]. These researchers identified the second phase particles in an annealed Zr-4 sample to be primarily the hexagonal, Laves-phase C14 Zr(Fe, Cr), type.…”

Section: 21mentioning

confidence: 99%

Modeling of Some Physical Properties of Zirconium Alloys for Nuclear Applications in Support of UFD Campaign

Glazoff¹

2013

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Zirconium-based alloys Zircaloy-2 and Zircaloy-4 are widely used in the nuclear industry as cladding materials for light water reactor (LWR) fuels. These materials display a very good combination of properties such as low neutron absorption, creep behavior, stress-corrosion cracking resistance, reduced hydrogen uptake, corrosion and/or oxidation, especially in the case of Zircaloy-4. However, over the last couple of years, in the post-Fukushima Daiichi world, energetic efforts have been undertaken to improve fuel clad oxidation resistance during off-normal temperature excursions. Efforts have also been made to improve upon the already achieved levels of mechanical behavior and reduce hydrogen uptake. In order to facilitate the development of such novel materials, it is very important to achieve not only engineering control, but also a scientific understanding of the underlying material degradation mechanisms, both in working conditions and in storage of used nuclear fuel.This report strives to contribute to these efforts by constructing the thermodynamic models of both alloys; constructing of the respective phase diagrams, and oxidation mechanisms. A special emphasis was placed upon the role of zirconium suboxides in hydrogen uptake reduction and the atomic mechanisms of oxidation. To that end, computational thermodynamics calculations were conducted concurrently with first-principles atomistic modeling.

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Section: 21mentioning

confidence: 99%

Modeling of Some Physical Properties of Zirconium Alloys for Nuclear Applications in Support of UFD Campaign

Glazoff¹

2013

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“…In fact, the certainty of this choice will be strongly dependant on the capability of the contrasting technique to detect the disappearance of very small hydrides at the final stage of the dissolution process. In the present cir-cumstances we judged that it would be most advisable to choose the criteria that better agree with the highly referenced curve of Kearns [9] and the equilibrium solvus line by Zuzek et al [10], as done by other authors [3,4]. This comparison is shown in Figure 8.…”

Section: Terminal Solid Solubilitymentioning

confidence: 72%

Hydrogen Pick up in Zircaloy-4: Effects in the Dimensional Stability of Structural Components under Nuclear Reactor Operating Conditions

Vizcaı́no¹

2010

Engineering

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In the present work, the expansion coefficient due to hydrogen incorporation was measured for the axial direction of a Zircaloy-4 cooling channel, similar to that installed in the Atucha I PHWR, Argentina, trying to simulate the nuclear power reactor operating conditions. As a first step, the solubility curve of hydrogen in Zircloy-4 was determined by two techniques: differential scanning calorimetry and differential dilatometry. The comparison with classical literature curves showed a good agreement with them, although the calorimetric technique proved to be more accurate for these determinations. Dilatometry was able to detect the end of hydride dissolution from concentrations around 60 wppm-H up to 650 wppm-H, where the eutectoid reaction:      takes place (at 550 o C). We assume that this ability is a good indicator of the aptitude of the technique to measure dimensional changes in the given hydrogen concentration range. Then, the expansion of Zircaloy-4 homogeneously hydrided samples was measured at 300 o C, the typical operating temperature of a nuclear power reactor, obtaining a relative expansion of 2.21 × 10 -4 % per wppm-H. Considering the relative expansion observed for Zircaloy-4 at room temperature due to hydriding, starting from a hydrogen free sample, the total relative expansion rate is calculated to be 5.21 × 10 -4 % per wppm-H.

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“…Zuzek et al 10 have obtained phase diagrams experimentally that are topologically equivalent to Figure 2c for the ZrH 2 − 2c system. Recent first-principles calculations 3 have demonstrated the existence of a mechanical instability that exists in this system at low c via non-convexity with respect to strain.…”

Section: Introductionmentioning

confidence: 82%

“…3 The ZrH 2 − 2c hydride can accommodate large concentrations of hydrogen vacancies, c, and has a phase diagram that is topologically identical to that depicted in Figure 2c, with a two-phase region separating a hydrogen-rich tetragonal form of ZrH 2 − 2cα from a cubic form of ZrH 2 − 2cβ (with c α oc β ). See Zuzek et al 10 (in their phase diagrams, Zuzek et al have an inverted composition axis relative to our notation, the tetragonal phase is labelled ε and the cubic phase is δ). To be consistent with the predicted free energies for stoichiometric ZrH 2 (i.e., c = 0) and the experimental T versus c phase diagram with the form of Figure 2c, the free energy of this hydride as a function of composition and strain (i.e., e 2 and e 3 ) should be similar to those depicted in Figures 2a,b and 3.…”

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confidence: 99%

Mechanochemical spinodal decomposition: a phenomenological theory of phase transformations in multi-component, crystalline solids

2016

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We present a phenomenological treatment of diffusion-driven martensitic phase transformations in multi-component crystalline solids that arise from non-convex free energies in mechanical and chemical variables. The treatment describes diffusional phase transformations that are accompanied by symmetry-breaking structural changes of the crystal unit cell and reveals the importance of a mechanochemical spinodal, defined as the region in strain-composition space, where the free-energy density function is non-convex. The approach is relevant to phase transformations wherein the structural order parameters can be expressed as linear combinations of strains relative to a high-symmetry reference crystal. The governing equations describing mechanochemical spinodal decomposition are variationally derived from a free-energy density function that accounts for interfacial energy via gradients of the rapidly varying strain and composition fields. A robust computational framework for treating the coupled, higher-order diffusion and nonlinear strain gradient elasticity problems is presented. Because the local strains in an inhomogeneous, transforming microstructure can be finite, the elasticity problem must account for geometric nonlinearity. An evaluation of available experimental phase diagrams and first-principles free energies suggests that mechanochemical spinodal decomposition should occur in metal hydrides such as ZrH 2 − 2c . The rich physics that ensues is explored in several numerical examples in two and three dimensions, and the relevance of the mechanism is discussed in the context of important electrode materials for Li-ion batteries and high-temperature ceramics. INTRODUCTIONSpinodal decomposition is a continuous phase transformation mechanism occurring throughout a solid that is far enough from the equilibrium for its free-energy density to lose convexity with respect to an internal degree of freedom. The latter could include the local composition as in classical spinodal decomposition described by Cahn and Hilliard, 1 or a suitable non-conserved order parameter as in the theory by Allen and Cahn 2 for spinodal ordering. A key requirement for continuous transformations is that order parameters can be formulated to uniquely describe continuous paths connecting the various phases of the transformation. These phases then correspond to local minima on a single, continuous free-energy density surface in that order parameter space. For classical spinodal decomposition inside a miscibility gap, all phases have the same crystal structure and symmetry, and the order parameter is simply the local composition. The existence of a single, continuous free-energy density surface for all phases participating in a transformation implies, by geometric necessity, the presence of domains in order parameter space, where the free-energy density is non-convex. Reaching those domains through supersaturation (by externally varying temperature or composition) makes the solid susceptible to a generalised spinodal decomposition.Many import...

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The H-Zr (hydrogen-zirconium) system

Cited by 251 publications

References 68 publications

Modeling of Some Physical Properties of Zirconium Alloys for Nuclear Applications in Support of UFD Campaign

Modeling of Some Physical Properties of Zirconium Alloys for Nuclear Applications in Support of UFD Campaign

Hydrogen Pick up in Zircaloy-4: Effects in the Dimensional Stability of Structural Components under Nuclear Reactor Operating Conditions

Mechanochemical spinodal decomposition: a phenomenological theory of phase transformations in multi-component, crystalline solids

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