Experimental investigations were made of internal friction and Young's modulus defect in monocrystalline samples which contained between 1.3 and 7.6at%Ni. A wide range of oscillatory strain amplitudes was used, at 7 to 300K. Extensive data were obtained for frequencies around 100kHz, and were compared with results for the same crystals at a frequency of about 1kHz. The strain-amplitude dependence of the anelastic strain amplitude, and of the average friction stress acting upon a dislocation due to solute atoms, were also analyzed. Several stages were identified in the strain-amplitude dependence of the internal friction and the Young's modulus defect, for all alloy compositions, at various temperatures and in different frequency ranges. At a frequency of 100kHz, using low temperatures and low strain amplitudes (10-7 to 10-5), the amplitude-dependent internal friction and the Young's modulus defect were essentially temperature-independent. They were attributed to a purely hysteretic internal friction component. At higher strain amplitudes, a transition stage and steep strain-amplitude dependence of the internal friction and the Young's modulus defect were observed. This was followed by saturation at the highest strain amplitudes which were used. These stages were temperature- and frequency-dependent and were assumed to be due to the thermally activated motion of dislocations. It was suggested that the observed regularities over the entire strain amplitude, temperature and frequency ranges corresponded to the motion of dislocations in a 2-component system of obstacles. These components were either weak but long-ranged ones, due to the elastic interaction of dislocations with solute atoms distributed within the bulk of the crystal, or strong short-range ones which were due to the interaction of dislocations with solute atoms that were distributed close to dislocation glide planes.

Strain Amplitude Dependent Anelasticity in Cu-Ni Solid Solution due to Thermally Activated and Athermal Dislocation/Point-Obstacle Interactions. S.Kustov, G.Gremaud, W.Benoit, S.Golyandin, K.Sapozhnikov, Y.Nishino, S.Asano: Journal of Applied Physics, 1999, 85[3], 1444-59