High-temperature structure, elasticity, and thermal expansion of ε-ZrH1.8

Zirconium hydride is a promising candidate material for nuclear microreactor applications as a solid-state moderator component, owing to its favorable neutronics properties and good thermal stability over other metal hydrides. Here, in the present work, the crystal structure, thermal expansion, and...

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Bibliographic Details
Published in:Journal of nuclear materials 2024-10, Vol.603
Main Authors: Torres, James R., Mizzi, Christopher Adam, Rehn, Daniel Adam, Smith, Tyler, Paisner, Scarlett Widgeon, Terricabras, Adrien J., Parkison, Darren Mitchell Sherman, Vogel, Sven C., Kohnert, Caitlin Anne, Hayne, Mathew Lindsay, Nizolek, Thomas Joseph, Torrez, Michael Albert, Munroe, Tannor Thomas John, Maiorov, Boris Alfredo, Saleh, Tarik A., Shivprasad, Aditya Prahlad
Format: Article
Language:English
Subjects:
Crystal structure
Elasticity
Metal hydrides
Neutron diffraction
Thermal expansion
Ultrasonics
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Summary:Zirconium hydride is a promising candidate material for nuclear microreactor applications as a solid-state moderator component, owing to its favorable neutronics properties and good thermal stability over other metal hydrides. Here, in the present work, the crystal structure, thermal expansion, and elastic properties of the hydrogen-rich ε phase hydride were measured at elevated temperatures in the range 300–900 K. Samples were prepared by direct hydriding Zircaloy-4 metal – a nuclear-grade zirconium alloy. Room-temperature lattice parameters agree well with those reported from literature for unalloyed zirconium hydride and fall within an observed quadratic H-content dependence. The coefficients of thermal expansion, determined from lattice expansion and dilatometry, agree well within our work but were about 30 % lower than those reported by others for unalloyed hydrides. Density functional theory-based molecular dynamics simulations were used to compare with thermal expansion and elasticity measurements. Results showed lattice parameter temperature dependence and slope of thermal expansion align with those from measurements. Based on diffraction scans at select temperatures, ε phase remained stable in air up to at least 770 K. Likewise, dilatometry showed smooth thermal expansion up to the thermal decomposition temperature around 950 K. The precise decomposition temperature was not determined via diffraction due to sparse scanning. The complete elastic property measurements were gathered for ε-phase Ziracloy-4 hydride for the first time. Young's modulus was lower compared to the metal and δ hydride phases. High-temperature elasticity measurements were limited to
ISSN:0022-3115