HYDROGEN INTERNAL-FRICTION PEAK AND INTERACTION OF DISSOLVED INTERSTITIAL ATOMS IN NB AND TA

Internal friction due to diffusion of H and D atoms under stress was calculated for Ta(Nb)-H(D)-O(N) alloys. The long-range strain-induced (elastic) interaction was supplemented by a repulsive interaction in the nearest coordination shells due to a screened Coulomb interaction between charged interstitials. Short-range order in the interstitial solid solution was simulated by the Monte Carlo method. It was suggested that the interatomic interaction affects internal friction by changing the arrangement and the energy of H or D atoms in solid solution and therefore the activation energy of the relaxation process. Computer simulation was carried out with calculated values of energies of elastic interaction and with different radii of additional repulsive interaction. The calculated spectra are in good agreement with experimental data when the repulsive interaction extends out to the third coordination shell. The strain-induced interaction model, when supplemented by repulsion in the three nearest shells, is a useful description of these solid solutions.