Nb-1 wt% Zr polycrystalline and single crystalline samples were submitted to annealing, at pressure of 2.5 x 10-8 Torr and subsequently annealed in an oxygen atmosphere for three hours, in a temperature of 1170 K in oxygen at partial pressure of 5 x 10-5 Torr. Internal friction measurements as a function of temperature were performed between 300 K and 650 K, using a torsion pendulum inverted Kê-type operating in a frequency oscillation in the hertz bandwidth. Three internal friction peaks, which were assigned as Nb-O, Zr-O and Nb-N peaks were observed in oxidized single crystal sample and the relaxation parameters of the three peaks were obtained.

Mechanical spectroscopy measurements have been extensively used in the last decades to obtain information about many aspects of the behavior of solutes in metallic materials. Metals of body-centered cubic lattice that contain heavy interstitial elements (oxygen, nitrogen and carbon) in solid solution, present anelastic relaxation peaks when submitted to cyclic tensions, due to process know stress-induced ordering. Internal friction and frequency as a function of temperature were performed between 300 K and 650 K in a polycrystalline sample of Nb, for three distinct conditions, using a torsion pendulum inverted Kê-type operating in a frequency oscillation between 1Hz and 10 Hz range, with a heating rate of 1 K/min and pressure lower than 2 x 10-5 mbar. The experimental spectra obtained for each condition of the sample, were decomposed by the successive subtraction method in elementary Debye peaks. The following metal-interstitial interactions were identified: Nb-O and Nb-N for all conditions of the sample. From the anelastic relaxation parameters obtained (relaxation strength, peak temperature, activation energy and relaxation time) and lattice parameter (obtained from x ray diffraction), the determination of the oxygen and nitrogen interstitial diffusion coefficient in Nb was possible, for each condition of the sample