Kinetics of the Migration and Clustering of Extrinsic Gas in bcc Metals

    Volume 4, Issue 9 (October 2007)

    ISSN: 1546-962X

    CODEN: JAIOAD

    Published Online: 9 October 2007

    Page Count: 13


    Deo, C. S.
    Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia

    Srinivasan, S. G.
    MST-8, MS G755, Los Alamos National Laboratory, Los Alamos, New Mexico

    Baskes, M. I.
    MST-8, MS G755, Los Alamos National Laboratory, Los Alamos, New Mexico

    Maloy, S. A.
    MST-8, MS G755, Los Alamos National Laboratory, Los Alamos, New Mexico

    James, M. R.
    D-5, MS K575, Los Alamos National Laboratory, Los Alamos, New Mexico

    Okuniewski, M.
    Department of Nuclear Engineering, University of Illinois, Urbana, Illinois

    Stubbins, J.
    Department of Nuclear Engineering, University of Illinois, Urbana, Illinois

    (Received 19 June 2006; accepted 26 August 2007)

    Abstract

    We study the mechanisms by which gas atoms such as helium and hydrogen diffuse and interact with other defects in bcc metals and investigate the effect of these mechanisms on the nucleation of embryonic gas bubbles. Large quantities of helium and hydrogen are produced due to spallation and transmutation in structural materials in fusion and accelerator-driven reactors. The long time evolution of the extrinsic gas atoms and their accumulation at vacancies is studied using a kinetic Monte Carlo algorithm that is parameterized by the migration energies of the point defect entities. First-order reaction kinetics are observed when gas clusters with vacancies. If gas-gas clustering is allowed, mixed-order diffusion limited kinetics are observed. When dissociation of gas from clusters is allowed, gas-vacancy clusters survive to steady state while gas-gas clusters dissolve. We obtain cluster size distributions and reaction rate constants that can be used to quantify microstructural evolution of the irradiated metal.


    Paper ID: JAI100698

    DOI: 10.1520/JAI100698

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    Title Kinetics of the Migration and Clustering of Extrinsic Gas in bcc Metals
    Symposium 23rd Symposium on Effects of Radiation on Materials, 2006-06-15
    Committee E10