STP1046

    The Influence of Microstructure and Solutes on Void Formation and Void Growth in Irradiated Materials

    Published: Jan 1990


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    Abstract

    In the present work, the reaction rate theory of radiation effects has been used to compare the relative significance of several microstructure-dependent mechanisms that influence void formation and growth. Some of these mechanisms reduce the time required for a gas-stabilized bubble to reach the critical size for void formation by either increasing the gas accumulation rate or by reducing the critical number of gas atoms required for void formation. Void growth can be increased by mechanisms that lead to more efficient partitioning of vacancies to the voids. Several of these mechanisms involve the presence of precipitates; they are: helium collection at matrix-precipitate interfaces, point-defect collection at matrix-precipitate interfaces, the interface energy credit due to the coupled growth of a cavity-precipitate pair and possible local bias effects due to matrix-precipitate interface strains. The influence of the total precipitate sink strength on the evolution of matrix cavities has also been examined. Other mechanisms included in this comparison are helium collection at network dislocations and solute trapping. The results of the comparison indicate that a “favorable” microstructure can lead to large reductions in the void formation time and increases in the void growth rate. The influence of precipitates shown in this work is consistent with the experimental observation that the largest voids in irradiated alloys are frequently associated with these particles. Helium and point-defect collection are shown to be the most significant precipitate effects. The former influences primarily the incubation time and the latter, both the nucleation time and the swelling rate. Helium trapping at dislocations can also accelerate void formation to a great degree when some fraction of the trapped helium is distributed to bubbles.

    Keywords:

    bubbles, cavities, precipitate effects, radiation effects, rate theory, stainless steels, void nucleation, void growth, void swelling


    Author Information:

    Stoller, RE
    Research staff member and group leader, Oak Ridge National Laboratory, Oak Ridge, TN

    Mansur, LK
    Research staff member and group leader, Oak Ridge National Laboratory, Oak Ridge, TN


    Paper ID: STP24662S

    Committee/Subcommittee: E10.02

    DOI: 10.1520/STP24662S


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