Gas diffusion and temperature dependence of bubble nucleation during irradiation

A. J. E. Foreman, Bachu Narain Singh

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    The continuous production of gases at relatively high rates under fusion irradiation conditions may enhance the nucleation of cavities. This can cause dimensional changes and could induce embrittlement arising from gas accumulation on grain boundaries. Computer calculations have been made of the diatomic nucleation of helium bubbles, assuming helium to diffuse substitutionally, with radiation-enhanced diffusion at lower temperatures. The calculated temperature dependence of the bubble density shows excellent agreement with that observed in 600 MeV proton irradiations, including a reduction in activation energy below Tm/2. The coalescence of diatomic nuclei due to Brownian motion markedly improves the agreement and also provides a well-defined terminal density. Bubble nucleation by this mechanism is sufficiently fast to inhibit any appreciable initial loss of gas to grain boundaries during the nucleation period, provided that incubation effects do not occur.
    Original languageEnglish
    JournalJournal of Nuclear Materials
    Volume141-143
    Pages (from-to)672-676
    ISSN0022-3115
    Publication statusPublished - 1986

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