Hard X-ray diffraction scanning tomography with sub-micrometre spatial resolution: application to an annealed γ-U0.85Mo0.15 particle

It is demonstrated that scanning X-ray diffraction tomography of heterogeneous and polycrystalline samples can provide real-space semi-quantitative three-dimensional structural information at a submicrometre spatial resolution. The capabilities of this technique are illustrated by the study of a slice of a spherical particle consisting of a UMo core (about 37 mu m in diameter) surrounded by a UMoAl shell (5 mu m thick). The technique allows precise characterization of the embedded UMo/UMoAl interface where the phases alpha-U (in the core), UAl2 and U6Mo4Al43 (in the shell) are found. Moreover, an unexpected phase (UC) is detected at a trace level. It is shown that the thickness of the UMoAl shell is locally anticorrelated with the amount of UC, suggesting that this phase plays a protective role in inhibiting thermally activated Al diffusion in UMo.