In order to model the diffusion in multicomponent and multiphase systems we define and use the volume fixed frame of reference. In this unique frame all diffusion fluxes are expressed by the combined Darken-Nernst-Planck formulae. The components mobility is estimated using the NIST data and Calphad approach. The resulting CADiff method is used for the modeling (inter)diffusion process in the multicomponent diffusion multiple. We shows results for the IN718-Rene88 terminal compositions. Comparison of the simulation results with experimental data shows good agreement. The presented CADiff method allows to model interdiffusion in multicomponent non-ideal systems. When the thermodynamical data are available, the method allows to include reactions, variable partial molar volumes and effect of stress.