STP1125

    Spatial Self-Organization of a Void System in Irradiated Metals

    Published: Jan 1992


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    Abstract

    Spatially random void distribution results in small spatial variations of void growth rate from void to void With a constant density of dislocations and continuous point-defect generation, an average net vacancy flux towards a void decreases with increasing void concentration So, at a comparatively high void density, it can be insufficient to damp crucial enhancement of small deviations of void sizes from an average value because of vacancy emission from voids or strong stochastic fluctuations of void growth rate due to the Browman-like motion of point defects in the crystal or the production of point defects in discrete packages introduced by collision cascades All these possibilities are investigated and the corresponding conditions of the spatially random void distribution instability are obtained These instability conditions taken together have good agreement with experimental data and allow the formation of spatially ordered void distributions in the whole temperature range of the void swelling of irradiated metals

    A void stabilizes its growth in time at the expense of the shrinkage of neighboring voids and as a consequence of the increase of the spatial volume from which this void receives point defects generated by continuous irradiation As a result, around each void surviving in the instability conditions a zone free of other voids exists, and the void distribution is inevitably ordered in space in some manner The volume of this zone determines the degree of spatial void ordering.

    Void ordering is a result of spatially mhomogeneous void shrinkage after the completion of the void nucleation process Only “ordered” voids survive The influence of the amsotropic transport of self-interstitial atoms and of void motion on the formation of spatially ordered void distributions is also discussed.

    Keywords:

    radiation, point defects, voids, instability, void shrinkage, vacancy emission, stochastic fluctuations, collision cascades, distribution function, nonequilibnum phase transition, void ordering


    Author Information:

    Koptelov, EA
    Head of Radiation Physics Group and scientist, Institute for Nuclear Research, Academy of Sciences of the USSR, Moscow,

    Semenov, AA
    Head of Radiation Physics Group and scientist, Institute for Nuclear Research, Academy of Sciences of the USSR, Moscow,


    Paper ID: STP17896S

    Committee/Subcommittee: E10.08

    DOI: 10.1520/STP17896S


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