Hydride reorientation in Zircaloy-4 examined by in situ synchrotron X-ray diffraction

Weekes, H.E.; Jones, N.G.; Lindley, T.C.; Dye, David

doi:10.1016/j.jnucmat.2016.05.029

Cited by 25 publications

(9 citation statements)

References 36 publications

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“…In this sense, our results do not include important features of the Zr hydride particles such as their elongated shape and/or their orientation. Excellent recent examples of experimental characterization displaying all of these structure complexities exist now in the literature [99][100][101]. They can act, however, as a good springboard from which to connect to other methods such as phase field simulations [27,102,103], or orientation-dependent precipitation models [104,105].…”

Section: Discussionmentioning

confidence: 99%

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: Discussionmentioning

confidence: 99%

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

Reyes

Shah

et al. 2020

Materials

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“…Cooling under an applied stress may affect the resultant hydride distribution and the hydride fracture toughness [23,24]. Plastically deforming the specimen in compression before, during, or after hydriding may have applications to the study of heterogeneous precipitation of hydrides at dislocations [25].…”

Section: Comments On Hydrogen Homogeneitymentioning

confidence: 99%

On the Development of a Novel Technique for Hydriding Using Zirconium Hydride Powder

2019

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Zirconium alloys are of particular interest for applications within the nuclear industry given their low thermal neutron capture cross-section to strength ratios, adequate corrosion resistance, and high temperature stability. However, zirconium alloys are susceptible to hydrogen embrittlement, which limits the service lives of zirconium alloy components in reactor systems. Hydrogen charging, or hydriding, is a technique used to artificially age ex-service or as-received material to predetermined hydrogen concentrations for material testing on representative specimens. This study presents a thermo-mechanical approach to precision hydriding. Discussion on the development and commissioning of a suitable apparatus, called the Thermomechanical Hydrogen Ingression System (THIS), is provided. Hydriding results from commissioning as well as several repeatability tests are reported, which demonstrate the viability of the technique and equipment.

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“…Samples were then allowed to furnace cool for 24 hours to form stable δ-hydride features. The details of the hydrogen charging technique can be found in the work of Weekes et al [10]. The inert gas fusion (IGF) technique was used to measure the hydrogen concentration, as outlined in the ASTM E1447 standard [7].…”

Section: Specimen Preparationmentioning

confidence: 99%

The Effect of Grain Boundaries and Second-Phase Particles on Hydride Precipitation in Zirconium Alloys

et al. 2018

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Understanding the precipitation of brittle hydride phases is crucial in establishing a failure criterion for various zirconium alloy nuclear fuel cladding. Accordingly, it is important to quantify the sensitivity of hydride precipitation to the component microstructure. This experimental investigation focuses on two microstructural characteristics and their role as hydride nucleation sites: The grain size and the alloy chemical composition. Samples of commercially pure zirconium (Zr-702) and Zircaloy-4, each with a wide range of grain sizes, were hydrided to 100 ppm and micrographs of the hydride distribution were optically analyzed for inter-granular and intra-granular precipitate sites. For most grain sizes, it was found that a significantly lower fraction of the precipitated hydrides nucleated at grain boundaries in Zircaloy-4 than in Zr-702, suggesting that a higher SPP content encourages the formation of intra-granular hydrides. Moreover, this effect became more prominent as the grain size increased; large-grain specimens contained a higher fraction of intra-granular hydrides than small-grain specimens of both Zr-702 and Zircaloy-4, highlighting the potency of grain boundaries as nucleation sites and how SPPs can influence the hydride distribution profile.

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Hydride reorientation in Zircaloy-4 examined by in situ synchrotron X-ray diffraction

Cited by 25 publications

References 36 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

On the Development of a Novel Technique for Hydriding Using Zirconium Hydride Powder

The Effect of Grain Boundaries and Second-Phase Particles on Hydride Precipitation in Zirconium Alloys

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