Measurements of internal friction as a function of temperature were carried out in samples which contained various amounts of interstitial solutes (O, N). One sample initially contained only N as an interstitial solute. The experimental spectra of internal friction as a function of temperature were obtained by using a torsion pendulum of inverted Kê-type, and were resolved (by using the method of successive subtraction) into a series of constituent Debye peaks that corresponded to different interactions. For each relaxation process, it was possible to obtain the height and temperature of the peak, the activation energy and the relaxation time. The height, shape and temperature of these peaks depended upon the concentration of interstitial elements. The observed peaks were associated with matrix-interstitial (Nb---O, Nb---N) and interstitial–interstitial (O---N) interaction processes.

Effect of Interstitial Impurities on Internal Friction Measurements in Niobium. O.Florêncio, C.R.Grandini, W.J.Botta F, P.R.Guedes, P.S.Silva: Materials Science and Engineering A, 2004, 370[1-2], 131-4