The Hydrogen Influence upon Oxygen Snoek Relaxation in Nb-Ti Alloys

Abstract
The oxygen Snoek peak was measured at frequency f = 1..10 Hz for Nb-0.05 wt.%O and 48wt.%Nb - 52wt.%Ti - 0.1wt.%O alloys. The alloys hydrogenizing leads to the decrease of height and to the shift of the temperature of oxygen Snoek peak for Nb-O and Nb-Ti-O alloys both. The new approach for computer simulation of temperature dependent internal friction spectrum has been carried out for the study of the hydrogen influence mechanism. The following pair interactions have been taken into account : H-O, H-Ti, O-Ti, H-H, O-O. The long-ranged strain-induced (elastic) interaction model, supplemented by short-range Coulomb repulsion for H-H, H-O, O-O and "chemical" interaction for H-substitutional and O-substitutional atom was used for simulation. The influence of the interaction on atoms arrangement (short-range order), the activation energy and the pre-exponential factor of oxygen relaxation time was taken into account. It is shown that the influence of hydrogen on oxygen Snoek peak can be explained by the influence of hydrogen on energy of oxygen atoms in solid solution and therefore on activation energy of diffusion.