Investigating the structure of Splat-Cooled Uranium and Uranium-Molybdenum alloys

Xander Warren, Tom Scott

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Abstract

Splat cooled uranium has been used in a range of studies for around 50 years, coming into focus more recently as a source of ‘glassy’ or ‘amorphous’ uranium for super-conductor and electromagnetic experiments. But apart from a very cursory optical metallographic study in the early 60’s[1,2], no physical characterisation work has ever been done. The range of new techniques which have been developed since the initial study have significantly broadened the possible approaches, and have led to a truly novel study. Perhaps the most significant finding of the study has been the demonstration that using a splat cooling method with cooling rates of the order of 106 K/s it has been possible to preserve the high temperature (existing for T > 775o C) γ-phase at room temperature (RT) in pure uranium, something which was hither-to considered impossible. The γ-phase observed using EBSD were both intra-granular micro-grains (typically siting along sub-boundaries) and inter-granular micro-grains. This correlates with XRD measurements made by the manufacturing research group [N-TH Kim-Ngan et al. JdA2012 Friday talk]. Given the relative strength of the XRD signal, it is thought that the γ-phase is concentrated at the outer surfaces of the splat (which, as the point of the most rapid cooling, makes it the most likely position for the preservation of a metastable phase) and the majority of the phase is consequently removed during the electropolishing required to yield a suitable surface for EBSD analysis. As part of the same study, the structure of a range of different splat cooled uranium-molybdenum alloys (4, 11 and 15 at%) has been investigated to determine the stabilising effects of the alloying element. The XRD data shows that the 4 at% Mo sample is a mix of α'+γ, with the 11 at% Mo effectively γ0 and the 15 at% Mo the expected pure γ-phase.[1] S. Isserow; Early work on rapidly solidified uranium , Journal of Materials Science, 1981,16, 3214-3215; [2] A. R. Kaufmann; Nuclear Metals Inc. (1963); Method and apparatus for making powder, US-3099041
Original languageEnglish
Number of pages1
Publication statusPublished - 1 Jun 2012
Event42èmes Journées des Actinides (42nd JdA) -
Duration: 1 Jun 2012 → …

Conference

Conference42èmes Journées des Actinides (42nd JdA)
Period1/06/12 → …

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