A combination of experimental techniques and molecular dynamics computer simulation was used to investigate diffusion dynamics in Al80Ni20 melts. Experimentally, the self-diffusion coefficient of Ni was measured by using the long-capillary method and by quasi-elastic neutron scattering. The long-capillary method also yielded the interdiffusion coefficient. Whereas the experiments were performed in the normal liquid state, the simulations also provided a determination of self-diffusion and interdiffusion constants in the undercooled regime. The simulation results showed good agreement with experimental data. At 715 to 3000K, the interdiffusion coefficient was larger than the self-diffusion constants. Furthermore, the simulation showed that this difference became larger in the undercooled regime. This result could be attributed to a relatively strong temperature dependence of the thermodynamic factor which described the thermodynamic driving force for interdiffusion. The simulations also indicated that the Darken equation was a good approximation, even in the undercooled regime. This implied that dynamic cross-correlations played a minor role in the temperature range under consideration.

Self-Diffusion and Interdiffusion in Al80Ni20 Melts - Simulation and Experiment. J.Horbach, S.K.Das, A.Griesche, M.P.Macht, G.Frohberg, A.Meyer: Physical Review B, 2007, 75[17], 174304 (8pp)