STP1046

    Electron Irradiation-Induced Amorphization of Precipitates in Zircaloy-2

    Published: Jan 1990


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    Abstract

    The crystalline-amorphous transformation of Zr2(Ni,Fe) precipitates in Zircaloy by electron irradiation has been studied in the high voltage electron microscope at temperatures ranging from 92 to 283 K and dose rates between 10-3 and 4 × 10-2 dpa/s. The dose-to-amorphization was found to increase exponentially with temperature and to decrease with increasing dose rate. The occurrence of the transformation was modeled by calculating the increase in free energy because of irradiation effects: accumulation of point defects and lattice disordering. The time-dependent diffusion equation with recombination was solved to find the interstitial and vacancy concentrations as functions of dose, dose rate, and temperature. Random recombination was the assumed disordering mechanism. The transformation was assumed to occur when the free energy increase of the crystalline phase became equal to the difference in free energy between the amorphous state and the unirradiated crystal. The dose-to-amor phization predicted by the model agreed well with experimental results for reasonable values of the fitting parameters.

    Keywords:

    Zircaloy-2, crystalline-amorphous transformation, irradiation effects, energy


    Author Information:

    Motta, AT
    University of California at Berkeley, Berkeley, CA

    Olander, DR
    University of California at Berkeley, Berkeley, CA

    Machiels, AJ
    Electric Power Research Institute, Palo Alto, CA


    Paper ID: STP24661S

    Committee/Subcommittee: E10.03

    DOI: 10.1520/STP24661S


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