Theoretical evaluation of neutron scattering intensities, partial structure factors, and diffusion coefficients of the alloy of the peculiar metal Bi in Cu-Bi alloy

Abstract

Lebowitz's solution of C_ij⁰(r) for binary mixtures and a perturbation with a square-well attractive tail has been applied to compute three partial structure factors S₁₁(k), S₂₂(k), and S₁₂(k) of molten Cu-Bi alloy, which shows some sort of inhomogeneities in the distribution of the constituents. The scattering intensities at various concentrations and at different temperatures obtained from these partial structure factors compare satisfactorily with the experimental results. From the partial structure factors, the Bhatia-Thornton structure factors S_NN(k), S_CC(k), and S_NC(k) are computed for the Cu-Bi melts at various concentrations. It is found that in the case of this peculiar alloy the potential parameters are found to be concentration dependent to generate the scattering intensities. The compressibilities at various concentrations of Cu have been computed from the Kirkwood-Buff formula while the diffusion coefficients have been computed from Helfand's linear-trajectory principle for mixtures.