Phonon dispersion in binary metallic glasses

Abstract

The theoretical computation of the phonon dynamics of two binary metallic glasses Zr67Ni33 and Co67Zr33 have been studied from the model potential formalism using three different theoretical models proposed by Hubbard-Beeby, Takeno-Goda, and Bhatia-Singh. Five local field correction functions, viz., Hartree, Taylor, Ichimaru-Utsumi, Farid et al., and Sarkar et al., are used for the first time in the present investigation to study the screening influence on the aforesaid properties. The pair potential is computed in the Wills-Harrison form and used to study the eigenfrequencies of longitudinal and transverse phonon modes. The present data on phonon dispersion curves of the Zr67Ni33 glass are compared with the available MD results at different temperatures. To explain the electron-ion interaction, the pseudo-alloy-atom model is applied for the first time instead of the Vegard’s law. Further, thermodynamic and elastic properties have also been calculated from the elastic part of the phonon dispersion curves. Computed yielding of the Zr67Ni33 glass is found in fair agreement with the available data.