Microstructural Characterization of U-Nb-Zr, U-Mo-Nb, and U-Mo-Ti Alloys via Electron Microscopy

    Authors

    A. Ewh; E. Perez; D. D. Keiser;Y. H. Sohn

    Comments

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    Abbreviated Journal Title

    J. Phase Equilib. Diffus.

    Keywords

    experimental phase equilibria; isothermal equilibration; materials; characterization; metallic alloys; phase equilibria; ternary phase; diagram; transmission electron microscopy; IRRADIATION BEHAVIOR; AL; ALUMINUM; GROWTH; FUELS; Chemistry, Physical; Materials Science, Multidisciplinary; Metallurgy &; Metallurgical Engineering

    Abstract

    Ternary uranium molybdenum alloys are being examined for use as dispersion and monolithic nuclear fuels in research and test reactors. In this study, three such ternary alloys, with compositions U-10Nb-4Zr, U-8Mo-3Nb, and U-7Mo-3Ti in wt.%, were examined using scanning electron microscopy (SEM), x-ray diffraction (XRD), and transmission electron microscopy (TEM) with high angle annular dark field (HAADF) imaging via scanning transmission electron microscopy (STEM). These alloys were homogenized at 950 degrees C for 96 h and were expected to be single-phase bcc-gamma-U. However, upon examination, it was determined that despite homogenization, each of the alloys contained a small volume fraction precipitate phase. Through SEM and XRD, it was confirmed that the matrix retained the bcc-gamma-U phase. TEM specimens were prepared using site-specific focused ion beam ( FIB) in situ lift out (INLO) technique to include at least one precipitate from each alloy. By electron diffraction, the precipitate phases for the U-10Nb-4Zr, U-8Mo-3Nb, and U-7Mo-3Ti alloys were identified as bcc-(Nb, Zr), bcc-(Mo,Nb), and bcc-(Mo,Ti) solid solutions, respectively. The composition and phase information collected in this study was then used to construct ternary isotherms for each of these alloys at 950 degrees C.

    Journal Title

    Journal of Phase Equilibria and Diffusion

    Volume

    31

    Issue/Number

    3

    Publication Date

    1-1-2010

    Document Type

    Article; Proceedings Paper

    Language

    English

    First Page

    216

    Last Page

    222

    WOS Identifier

    WOS:000278094900002

    ISSN

    1547-7037

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