STP1304: Computer Model of Zener Relaxation

    Blanter, MS
    Professor and research engineer, Moscow State Academy of Instrumental Engineering and Information Science, Moscow,

    Kolesnikov, EV
    Professor and research engineer, Moscow State Academy of Instrumental Engineering and Information Science, Moscow,

    Pages: 12    Published: Jan 1997


    Abstract

    The model takes into account the fact that the displacements of atoms around each substitutional atom are governed by other substitutionals and their arrangement, that is, by short-range order. In general the symmetry of these displacements is lower than that ofcrystal lattice. Such a substitutional atom can be treated as an elastic dipole, the energy of which is dependent on the direction of the applied stress. It will diffuse under alternating stress and contribute to internal friction. The relaxation strength of each atom is taken as a strength of such elastic dipole. It was suggested that the activation energy of reorientation of the elastic dipole by jump of a substitutional atom is equal to the sum of the activation energy of tracer self-diffusion of one of the components of an alloy and the shift of energy of this atom in the force field of other substitutionals. The short-range order is simulated by the Monte Carlo method using pair interaction energies. The internal friction is calculated by summing up contributions of all substitutional atoms in accordance with the Debye equation. This model is equally good for both low and high concentrations. The model was used for analysis of internal friction and interaction energies for copper-zinc and silver-gold alloys. It gives the concentration dependence of relaxation strength like that found in the experiment. The interaction energies obtained by comparison of calculated peak temperatures with experimental ones are in a good agreement with the values obtained from diffuse scattering of X-rays and neutrons. This fact means that the difference between activation energies of diffusion and Zener relaxation can be attributed to substitutional interaction.

    Keywords:

    Zener relaxation, substitutional solid solutions, substitutional interaction, internal friction, copper-zinc alloys, silver-gold alloys


    Paper ID: STP11763S

    Committee/Subcommittee: E28.01

    DOI: 10.1520/STP11763S


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