Phase identification and morphology in rolled and annealed U-22.5at.%Zr foils

Abstract

A uranium-22.5 atomic% zirconium (U-22.5at.%Zr) alloy was characterized using transmission electron microscopy (TEM) following hot/cold-rolling, and again following a post-roll anneal as part of a novel fabrication process for the alloy. The TEM characterization included selected area electron diffraction, energy-dispersive X-ray spectroscopy (EDS), and bright field imaging. The δ-UZr2 phase fraction was 53.47% ± 0.09% in the rolled foil, substantially larger than the near-equilibrium value, 21.93% ± 0.03% in the annealed foil. Phase fractions and EDS analysis suggest a defect-driven U supersaturation in the δ-UZr2 phase. The lamellae mean random spacing was 0.21 μm ± 0.03 μm in the rolled foil and 0.70 μm ± 0.10 μm in the annealed foil. The δ-UZr2 L3 values were 0.11 μm ± 0.02 μm in the rolled foil and 0.16 μm ± 0.03 μm in the annealed foil. Zirconium inclusions in all foils were face-centered cubic (space group Fm-3 m), reinforcing that further investigations into the formation mechanism(s) and evolution of Zr inclusions are needed. Graphical abstract: [Figure not available: see fulltext.].