STP1304

    Dislocation Amplitude-Dependent Damping in Crystals

    Published: Jan 1997


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    Abstract

    Experimental investigations of the amplitude-frequency dependences of the dislocation amplitude-dependent damping (ADD), amplitude-dependent Young's modulus defect, and reversible nonlinear anelastic strain in a number of crystals served as a basis for the phenomenological description of the dislocation amplitude-dependent damping and quantitative analysis of its components. A rheological model with a corresponding differential equation has been constructed to describe the amplitude-frequency spectra of the dislocation anelasticity. Calculations according to the proposed model revealed a good correspondence with the experimental data. Some parameters of the model, accounting, for example, for the effective stress component and its dependence on the anelastic strain rate, are found in some cases to be the same for the macro — and reversible microplastic deformation.

    It has been shown that there exist at least three contributions, which may form the amplitude-frequency spectra of ADD due to dislocation motion: (i) overcoming of the internai stress “ripples” or internal stress field hysteresis, (ii) thermally activated, and (iii) athermal overcoming of point obstacles. These three components appear to be linked, in general, to the different levels of the defect structure of the crystals: interaction of dislocations, and perhaps, dislocation groups, and interaction of isolated dislocations with point obstacles. Limitations of the proposed phenomenological description are also discussed. Finally a qualitative microscopic description of dislocation nonlinear anelasticity is proposed, based on the “nonlocalized friction” concept.

    Keywords:

    dislocation amplitude-dependen damping, anelastic strain, effective stress, internal stress, thermally activated and athermal (micro)plasticity


    Author Information:

    Kustov, SB
    Senior scientist and scientist, A. F. Ioffe Physico-Technical Institute, Polytekhnicheskaja, St. Petersburg,

    Golyandin, SN
    Senior scientist and scientist, A. F. Ioffe Physico-Technical Institute, Polytekhnicheskaja, St. Petersburg,


    Paper ID: STP11737S

    Committee/Subcommittee: E28.10

    DOI: 10.1520/STP11737S


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