Kinetics-dominated interdiffusion in metallic glass-forming liquids

With a full set of experimentally obtained self- and interdiffusion coefficients, we are able to verify the relation between different transport coefficients in binary glass-forming Zr-Ni liquids. Despite a thermodynamic strong tendency of mixing, the interdiffusion is up to a factor of 2 slower than that predicted by the Darken equation. With the help of mode-coupling theory calculations, we identify that this is due to a slow, dominating kinetic contribution, arising from the dense packing of the melt, and the coupling of dynamics due to the strong Zr-Ni affinity. As a consequence, the cross correlation is on the order of 0.5 or less, whose contribution cannot be neglected, which seems to be a general feature of the glass-forming melts.