Anelastic relaxation techniques at kHz frequencies were used to investigate the mobility of H and D that were trapped by O impurities. An internal friction peak was detected at liquid N temperatures, the height of which (for a given O/[Ta+Nb] ratio) increased linearly with increasing H(D)/(Ta+Nb) ratio; thus indicating that more than one H or D atom could be trapped by a single O impurity. The peak was associated with a wide relaxation time spectrum which was due to the intrinsic compositional disorder of the alloy and to interactions among the O-H(D) complexes. These interactions gave rise to a temperature dependence of Curie-Weiss type for the relaxation strength, as well as to a decrease in the peak temperature with increasing H(D) content.

B.Coluzzi, A.Biscarini, R.Campanella, F.M.Mazzolai: Journal of Alloys and Compounds, 1995, 231, 279-86