An investigation was made of the dynamic internal friction of pure monocrystalline material during creep at homologous temperatures of about 0.5. The internal friction behavior could be explained in terms of a model which considered both the generation and motion of dislocations. This method was here extended to the case of constant-rate deformation at high temperatures. It was found that the constant-rate deformation was different to that in creep in that, in the former case, the strain rate remained constant while the flow stress changed with time or strain. In the latter case, the applied stress (or load) remained constant while the strain rate changed with time or strain. Transmission electron microscopic observations indicated that variations in Q-1 were associated with changes in the dislocation configurations. The changes in the dislocation configurations during constant-rate deformation were similar to those during creep at the same test temperature and similar strain rate. However, at larger strains more dislocations were present within the sub-grains than were present during steady-state creep. The variations in the internal friction versus strain for the 2 cases were correspondingly different.

H.Zhou, Q.P.Kong: Scripta Materialia, 1996, 34[7], 1171-7