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arXiv · 2109.10955

Nanoscale characterisation of hydrides and secondary phase particles in Zircaloy-4

Wenjun Lu·Paraskevas Kontis·Siyang Wang·Ruth Birch·Mark Wenman·Baptiste Gault·T. Ben Britton
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Abstract

The interaction of hydrogen and metals continues to be industrially relevant and is a critical part of creating and supporting a safety case for nuclear reactor operation. In the present work, we explore hydrogen storage and hydride formation in a zirconium alloy. We characterise the structure and interfaces of fine scale hydrides using scanning transmission electron microscopy (STEM) including energy dispersive spectroscopy (EDS/EDX), electron energy loss spectroscopy (EELS), and high-resolution STEM. Chemical characterisation is supported further with atom probe tomography (APT). Samples were prepared with cryo-focussed ion beam machining (cryo-FIB) and contain hydrides in {\alpha}-Zr matrix and hydrides associated with one FeCrZr secondary phase particle (SPP). Major findings include characterisation of different interface planes based upon the size of the hydrides and chemical redistribution of solute ahead of the hydride-metal interface. We also find significant (up to 6 at%) hydrogen retained in solution within the zirconium matrix and show a hydride with only 17 at% hydrogen, which is well below that of a {\xi}-phase stoichiometry suggesting it is an embryonic hydride. These findings help us understand the distribution of hydrogen and the nanoscale morphology of hydrides, which may influence the lifetime of zirconium-based nuclear fuel cladding.

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Wenjun Lu, Paraskevas Kontis, Siyang Wang, Ruth Birch, Mark Wenman, Baptiste Gault, T. Ben Britton. 2021-09-22. Nanoscale characterisation of hydrides and secondary phase particles in Zircaloy-4. https://arxiv.org/abs/2109.10955

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