The efficiency of void formation during annealing of irradiated molybdenum

J.H. Evans

    Research output: Book/ReportReport

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    Abstract

    Results are presented to demonstrate the high efficiency of vacancy retention that occurs when voids are formed by the annealing at 900°C of molybdenum samples neutron irradiated at 60°C. In the particular case examined the efficiency is shown to be some 50 times more than the theoretical maximum expected during the formation of voids under conventional high temperature neutron irradiation. Various aspects of this efficiency are discussed with particular reference to a recent position annihilation study of the processes taking place during annealing. A mechanism for the high vacancy retention is suggested that depends largely on the storage of vacancies in loop form during irradiation below the temperature of vacancy loop shrinkage and the transfer of vacancies to voids on annealing above this temperature. There seems to be only a small possibility that the mechanism could operate unintentionally in reactor
    situations. On the other hand by ensuring void nucleation the high efficiency of void production by the irradiation-annealing method might be used to advantage in providing inexpensive void samples for experimental purposes. Finally, it is noticed in passing that the behaviour of the vacancy loops could provide a simple explanation of the emperical 0.3 Tm threshold for conventional void formation in metals.
    Original languageEnglish
    Place of PublicationRoskilde, Denmark
    PublisherRisø National Laboratory
    Number of pages9
    Publication statusPublished - 1973
    SeriesRisø-M
    Number1641
    ISSN0418-6435

    Keywords

    • Risø-M-1641

    Cite this

    Evans, J. H. (1973). The efficiency of void formation during annealing of irradiated molybdenum. Roskilde, Denmark: Risø National Laboratory. Risø-M, No. 1641
    Evans, J.H. / The efficiency of void formation during annealing of irradiated molybdenum. Roskilde, Denmark : Risø National Laboratory, 1973. 9 p. (Risø-M; No. 1641).
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    abstract = "Results are presented to demonstrate the high efficiency of vacancy retention that occurs when voids are formed by the annealing at 900°C of molybdenum samples neutron irradiated at 60°C. In the particular case examined the efficiency is shown to be some 50 times more than the theoretical maximum expected during the formation of voids under conventional high temperature neutron irradiation. Various aspects of this efficiency are discussed with particular reference to a recent position annihilation study of the processes taking place during annealing. A mechanism for the high vacancy retention is suggested that depends largely on the storage of vacancies in loop form during irradiation below the temperature of vacancy loop shrinkage and the transfer of vacancies to voids on annealing above this temperature. There seems to be only a small possibility that the mechanism could operate unintentionally in reactorsituations. On the other hand by ensuring void nucleation the high efficiency of void production by the irradiation-annealing method might be used to advantage in providing inexpensive void samples for experimental purposes. Finally, it is noticed in passing that the behaviour of the vacancy loops could provide a simple explanation of the emperical 0.3 Tm threshold for conventional void formation in metals.",
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    Evans, JH 1973, The efficiency of void formation during annealing of irradiated molybdenum. Risø-M, no. 1641, Risø National Laboratory, Roskilde, Denmark.

    The efficiency of void formation during annealing of irradiated molybdenum. / Evans, J.H.

    Roskilde, Denmark : Risø National Laboratory, 1973. 9 p. (Risø-M; No. 1641).

    Research output: Book/ReportReport

    TY - RPRT

    T1 - The efficiency of void formation during annealing of irradiated molybdenum

    AU - Evans, J.H.

    PY - 1973

    Y1 - 1973

    N2 - Results are presented to demonstrate the high efficiency of vacancy retention that occurs when voids are formed by the annealing at 900°C of molybdenum samples neutron irradiated at 60°C. In the particular case examined the efficiency is shown to be some 50 times more than the theoretical maximum expected during the formation of voids under conventional high temperature neutron irradiation. Various aspects of this efficiency are discussed with particular reference to a recent position annihilation study of the processes taking place during annealing. A mechanism for the high vacancy retention is suggested that depends largely on the storage of vacancies in loop form during irradiation below the temperature of vacancy loop shrinkage and the transfer of vacancies to voids on annealing above this temperature. There seems to be only a small possibility that the mechanism could operate unintentionally in reactorsituations. On the other hand by ensuring void nucleation the high efficiency of void production by the irradiation-annealing method might be used to advantage in providing inexpensive void samples for experimental purposes. Finally, it is noticed in passing that the behaviour of the vacancy loops could provide a simple explanation of the emperical 0.3 Tm threshold for conventional void formation in metals.

    AB - Results are presented to demonstrate the high efficiency of vacancy retention that occurs when voids are formed by the annealing at 900°C of molybdenum samples neutron irradiated at 60°C. In the particular case examined the efficiency is shown to be some 50 times more than the theoretical maximum expected during the formation of voids under conventional high temperature neutron irradiation. Various aspects of this efficiency are discussed with particular reference to a recent position annihilation study of the processes taking place during annealing. A mechanism for the high vacancy retention is suggested that depends largely on the storage of vacancies in loop form during irradiation below the temperature of vacancy loop shrinkage and the transfer of vacancies to voids on annealing above this temperature. There seems to be only a small possibility that the mechanism could operate unintentionally in reactorsituations. On the other hand by ensuring void nucleation the high efficiency of void production by the irradiation-annealing method might be used to advantage in providing inexpensive void samples for experimental purposes. Finally, it is noticed in passing that the behaviour of the vacancy loops could provide a simple explanation of the emperical 0.3 Tm threshold for conventional void formation in metals.

    KW - Risø-M-1641

    M3 - Report

    BT - The efficiency of void formation during annealing of irradiated molybdenum

    PB - Risø National Laboratory

    CY - Roskilde, Denmark

    ER -

    Evans JH. The efficiency of void formation during annealing of irradiated molybdenum. Roskilde, Denmark: Risø National Laboratory, 1973. 9 p. (Risø-M; No. 1641).