Abstract:The characteristics of the mathematical models for concentration distributions such as smoothing property, approximation, tangency, shape preserving property and coordination were analysed, and application examples of the mathematical models were given. The results show that the equilibrium compositions of all components at any point on the two-dimensional plane of the Mo-Fe-Ni-Co diffusion quarternary can be calculated by means of the above mentioned mathematical models, and that the combination of the multi-component diffusion couple technique with the above models can be used to deal with diffusion problems and phase diagram calculation.

Key words: concentration diffusions　mathematical models　phase diagram calculations　diffusion