Phonon dispersion in amorphous Zr-Ni alloys

Longitudinal and transverse phonon dispersion curves for binary amorphous ZrxNi100-x (x=17, 33, 50, 67, 83) alloys have been obtained using two theoretical approaches, namely, Takeno and Goda's self-consistent phonon theory and Bhatia and Singh (BS) model for a hypothetical one-component metallic glass. The effective pair potentials for the alloys are obtained within the Wills and Harrison formulation, employing the concept of an effective atom. The phonon dispersion curves from BS model exhibit the chief characteristics of both the longitudinal and transverse modes of propagation obtained by the molecular dynamics (MD) simulation. e.g. the longitudinal mode shows oscillatory behaviour while the same is absent in the transverse mode. It suggests the suitability of the effective pair potential used in the calculation. The elastic constants and elastic Debye temperatures are calculated from the phonon dispersion curves. The results are found to be very close to those derived from MD and to the available experimental value