Temperature dependent elastic properties of γ-phase U - 8 wt% Mo

Polycrystalline elastic moduli and stiffness tensor components of γ-phase U - 8 wt% Mo have been determined by resonant ultrasound spectroscopy in the temperature range of 25-650 °C. The ambient temperature elastic properties are compared to results measured via other experimental methods and show reasonable agreement, though there is considerable variation of these properties within the literature at both the U - 8 wt% Mo composition and as a function of Mo concentration. The Young's modulus of U - 8 wt% Mo measured in this study decreases steadily with temperature at a rate that is slower than trends previously observed at similar Mo concentrations, though the difference is not statistically significant. This first measurement of the temperature dependent elastic stiffness tensor of a polycrystalline U-Mo alloy clarifies that the behavior of the Young's modulus is due to a strongly weakening C11 polycrystalline stiffness tensor component, along with milder decreases in C12 and C44. The unique partially auxetic properties recently predicted for single-crystalline U-Mo are discussed in regard to their possible impact on the polycrystalline behavior of the alloy.