Nauman has recently asked about the diffusion coefficients of Nb and Mo in Inconel 625. These coefficients can be accurately calculated (at a given temperature or even as a function of temperature) with DICTRA, the leading software package in the field of computational kinetics, developed by the Royal Institute of Technology (Stockholm, Sweden). The program uses the CALPHAD method (apporach), a commercial mobility database, as well as Thermo-Calc to perform necessary thermodynamic calculations. If these diffusion coefficients are still needed, I would suggest that Computational Thermodynamics Inc. ( snipped-for-privacy@calphad.com), a US-based consulting company, is contacted for more specific information. The Company's URL is
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Dr. K.