  Diffusion couple technique is an efficient tool for the estimating the
chemical diffusion coefficients. Typical experimental uncertainties of the
composition profile measurements complicate a correct determination of the
interdiffusion coefficients via the standard Boltzmann-Matano, Sauer-Freise or
the den Broeder methods, especially for systems with a strong compositional
dependence of the interdiffusion coefficient. A new approach for reliable
fitting of the experimental profiles with an improved behavior at both ends of
the diffusion couple is proposed and tested against the experimental data on
chemical diffusion in the system Fe-Ga
