A simple method for estimating the mass diffusion coefficient of a dilute binary liquid alloy, that sequentially used experimental data for the static structure factor and isothermal susceptibility of the solvent, was presented. Another method used the static structure factor alone, and a third method used the isothermal susceptibility alone. A fourth method simultaneously used the static structure factor and isothermal susceptibility. The significant factor was that these methods did not require information concerning the interatomic potential. Stability with respect to weights in the optimization process used was established, as well as some indication of the upper limits on the applicable solute concentration. Comparisons were made with results from a high-quality capillary experiment on Pb-1wt%Au liquid alloy performed under micro-gravity conditions, and with velocity autocorrelation estimates deduced from molecular dynamics simulations. The results suggested that the capillary experiments were influenced by reverse diffusion of the solvent, and actually measured an average of the mass diffusion coefficients, Dij, weighted by the equilibrium concentrations of the solvent, x1, and solute, x2, defined by: Dtot = x12D11 + x22D22. The three methods were required to provide upper and lower estimates for the mixed solvent–solute diffusion coefficient, which were not directly accessible from the experimental data, and revealed agreement with the experiment via Dtot.

Estimation of the Solute Diffusion Coefficient of a Dilute Liquid Alloy - Static Structure Factor and Isothermal Compressibility Estimates Obtained using the

Rational Function Approximation of the Radial Distribution. P.J.Scott, R.W.Smith: Journal of Physics - Condensed Matter, 2009, 21[33], 335104