STP1423

    Activated Slip Systems and Localized Straining of Irradiated Zr Alloys in Circumferential Loadings

    Published: Jan 2002


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    Abstract

    During the plastic deformation of irradiated Zr alloys, specific slip systems are activated. Indeed, the dislocation loops of <a> type are strong obstacles for the dislocations gliding on the classical prismatic planes. An increase in yield strength is observed. This allows the activation of other slip systems. The basal slip, having a <a> Burgers vector can interact with the irradiation-induced dislocation loops. This interaction leads to the annealing of the loops by various mechanisms and leads to the formation of dislocation free bands after limited plastic strain (channeling).

    TEM examinations of Zry-4 samples strained after irradiation have been performed. High density of basal slip has been observed on channels. With such a mechanism, the irradiated Zr alloys exhibit a strain-softening behavior for loading orientations allowing this kind of interaction. A modeling of the interaction between the gliding dislocations and the loops has been performed to analyze the channel formation kinetics. Fine element (FE) computation of strain-softening materials has shown strong effects on the plastic zone shape ahead of crack tips.

    The results are discussed, focusing on the impact of this behavior on the mechanical properties of irradiated cladding. Specific attention is given on hoop straining with respect to PCI, RIA, or axial splitting.

    Keywords:

    Zr alloys, irradiation, deformation, strain softening, dislocation channeling, crack propagation


    Author Information:

    Regnard, C
    CEA Grenoble, DEC, Grenoble Cedex

    Verhaeghe, B
    CEA Grenoble, DEC, Grenoble Cedex

    Lefebvre-Joud, F
    CEA Grenoble, DEC, Grenoble Cedex

    Lemaignan, C
    CEA Grenoble, DEC, Grenoble Cedex


    Paper ID: STP11398S

    Committee/Subcommittee: B10.02

    DOI: 10.1520/STP11398S


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