title: Atomic-scale Studies of Uranium Oxidation and Corrosion by Water Vapour.
abstract: Understanding the corrosion of uranium is important for its safe, long-term storage. Uranium metal corrodes rapidly in air, but the exact mechanism remains subject to debate. Atom Probe Tomography was used to investigate the surface microstructure of metallic depleted uranium specimens following polishing and exposure to moist air. A complex, corrugated metal-oxide interface was observed, with approximately 60 at.% oxygen content within the oxide. Interestingly, a very thin (~5 nm) interfacial layer of uranium hydride was observed at the oxide-metal interface. Exposure to deuterated water vapour produced an equivalent deuteride signal at the metal-oxide interface, confirming the hydride as originating via the water vapour oxidation mechanism. Hydroxide ions were detected uniformly throughout the oxide, yet showed reduced prominence at the metal interface. These results support a proposed mechanism for the oxidation of uranium in water vapour environments where the transport of hydroxyl species and the formation of hydride are key to understanding the observed behaviour.
authors.affiliation: University of Oxford, Department of Materials, Oxford, United Kingdom OX1 3PH.
authors.forename: T L
authors.initials: TL
authors.lastname: Martin
authors.affiliation: AWE, Aldermaston, Reading, Berkshire, United Kingdom, RG7 4PR.|Interface Analysis Centre, University of Bristol, H.H. Wills Physics Laboratory, Bristol, United Kingdom, BS2 1TL.
authors.forename: C
authors.initials: C
authors.lastname: Coe
authors.affiliation: University of Oxford, Department of Materials, Oxford, United Kingdom OX1 3PH.
authors.forename: P A J
authors.initials: PA
authors.lastname: Bagot
authors.affiliation: AWE, Aldermaston, Reading, Berkshire, United Kingdom, RG7 4PR.
authors.forename: P
authors.initials: P
authors.lastname: Morrall
authors.affiliation: University of Oxford, Department of Materials, Oxford, United Kingdom OX1 3PH.
authors.forename: G D W
authors.initials: GD
authors.lastname: Smith
authors.affiliation: Interface Analysis Centre, University of Bristol, H.H. Wills Physics Laboratory, Bristol, United Kingdom, BS2 1TL.
authors.forename: T
authors.initials: T
authors.lastname: Scott
authors.affiliation: University of Oxford, Department of Materials, Oxford, United Kingdom OX1 3PH.
authors.forename: M P
authors.initials: MP
authors.lastname: Moody