It was recalled that, following the discovery of the bamboo internal friction peak in bamboo-structured crystalline material, a new high-temperature internal friction peak (HT) had been observed at a higher temperature when the specimen was quenched from high temperatures. Previous internal friction experiments, involving free-decay measurements, had shown that this peak was characterized by a high relaxation strength and a high activation energy, and exhibited an anomalous amplitude-dependent effect. These characteristics were critically studied here by measuring the internal friction using a forced-vibration method. The HT peak was found to consist of 2 sub-peaks (HT-1, HT-2). The activation energy of the HT-1 peak was found to be 1.4eV, while the activation energy of the HT-2 peak was 2.1eV. On the basis of transmission electron microscopic observations, it was suggested that the higher-temperature sub-peak (HT-2) was due to the climb of straight edge dislocation segments in the network structure. The lower-temperature sub-peak (HT-1) was attributed to the gliding of jogged screw dislocation segments. The anomalous amplitude effect was suggested to be a result of the HT-1 peak.

L.X.Yuan, T.S.Kê, T.Ge: Philosophical Magazine A, 1997, 76[1], 107-18