Development of a statistical calculation model for the hydrogen diffusion parameters in metals and alloys

Diffusion of H in metals is very important as it leads to engineering problems associated with manufacturing and use of high strength steels, reactor materials, alloys for transporting and storing hydrogen, etc. In the developed statistical calculation model (SCM) the pre-exponential factor of hydrogen diffusion in metals has been calculated from first principle of statistical physics. Activation energy of hydrogen diffusion in all metals is determined by correlation with the melting point of these metals. For temperatures below 1000 K, the SCM model uses activation energies calculated from first principles. For the diffusion of H in Fe, Cu, Ti, Mo a very good agreement has been obtained between the values calculated using the Arrhenius equation and the SCM model over a wide temperature range. For the diffusion of H in Ag, Cr, Ni, W the lines calculated using the Arrhenius equation and the SCM model does not coincide, however, the difference in diffusion coefficients near melting point does not exceed 40%, which is a good indicator for using SCM-model. The SCM model allows for the prediction of hydrogen diffusion parameters for alloys. Thus, for Ni and Zr alloys, very good agreement between calculations and experiment were obtained.