Homogenization of diffusion in multicomponent liquids

Diffusion is a key kinetic factor determining chemical mixing and phase formation in liquids. In multicomponent systems, the presence of different elements makes it experimentally challenging to measure diffusivities and understand their mechanisms. Using a molecular dynamics simulation, we obtain the diffusion constants and the atomic process of a model Cantor alloy liquid made of five equimolar components. We show that the diffusivities conform remarkably well to the Arrhenius law in a wide range of temperature covering both the equilibrium and undercooled liquid regions. The activation energies for all the alloy elements with different bonding energies and atomic sizes are close to each other. The results suggest that the diffusivity in the multicomponent liquid tends to be homogenized by the components with marginal differences. This finding allows us to treat the different elements as a single type of atom, the pseudo-atom, for diffusional and maybe structural and physical properties in multicomponent liquids.