Ab initio molecular dynamics simulation of self-diffusion in Al-Si binary melts

Ab initio molecular dynamics simulations have been used to predict diffusion coefficients in Al-Si binary melts as a function of composition and temperature. The self-diffusion coefficients of Al and Si are obtained from the mean-squared displacements and velocity autocorrelation functions employing two different exchange correlation functionals. The Si-concentrations include 0, 7, 12 and 15 at% Si with temperature ranging from 900-1800 K. In these Al-Si melts, aluminum and silicon exhibit nearly identical diffusion coefficients. The first nearest neighbor-shell coordinations of Al and Si vary slightly with composition and temperature and exhibit no significant changes in the vicinity of the eutectic. The density of the binary liquids including the eutectic composition (Al-12 at% Si) showed linear dependence on temperature.