On the role of entropy in determining transport properties in metallic melts

We performed ab initio molecular dynamics simulations to study the relationship between dynamic and structural properties of liquid Al1-xNix alloys along the T = 1795 K isotherm. Our findings show a strong non-linear dependence of self-diffusion coefficients and the viscosity as a function of composition, in fair agreement with available experimental data. We demonstrate that this non-linear dependence can be related to the detailed description of local structural ordering and more particularly to a pronounced increase of icosahedral short range order (ISRO) in the Ni-rich composition range. We evidence that the composition dependence of local structural ordering is not captured by the Stokes-Einstein relation but can be understood in terms of the partial excess entropy approximated by the two-body contribution.