STP1529

    Measurement and Modeling of Second Phase Precipitation Kinetics in Zirconium Niobium Alloys

    Published: Apr 2012


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    Abstract

    Commercial zirconium alloys contain second phase particles (SPPs) that are precipitated during processing. These particles not only influence mechanical properties but more crucially also have a profound influence on the corrosion performance. To understand how to control evolution and size distribution of SPPs, it is necessary to know how alloy composition and process variables influence the precipitation kinetics. In this work, a detailed study has been performed of the precipitation kinetics in binary Zr-1 wt % Nb, Zr-2.6 wt % Nb, and ternary variants with added iron and tin. A numerical model has also been developed to predict the precipitation kinetics of β-Nb in niobium containing zirconium alloys. Precipitation has been tracked by synchrotron X-ray diffraction measurement of lattice parameter change in the zirconium matrix as solute is removed into SPPs. The X-ray data has been complemented by thermoelectric power measurements. The combination of these two approaches is shown to be effective in quantifying the overall precipitation kinetics of SPPs. The results confirm previous observations that without prior deformation, precipitation kinetics is very sluggish in the binary Zr-Nb system. Deformation accelerates precipitation, and this effect is much stronger for the 1 wt % Nb alloy than for 2.6 wt % Nb, because the supersatu-ration is least. Ternary additions also have a profound effect on the overall precipitation kinetics. Iron accelerates the rate of niobium loss from solution, whereas tin additions appear to increase the incubation time for the onset of precipitation of niobium.

    Keywords:

    zirconium alloys, precipitation kinetics, synchrotron X-ray, modeling


    Author Information:

    Ivermark, Maria
    Westinghouse Electric Sweden AB, Västerås,

    Robson, Joseph
    School of Materials, University of Manchester, Manchester,

    Preuss, Michael
    School of Materials, University of Manchester, Manchester,


    Paper ID: STP152920120007

    Committee/Subcommittee: B10.02

    DOI: 10.1520/STP152920120007


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