The oscillatory strain amplitude dependence of the acoustoplastic effect, and the absorption of the ultrasonic vibrations (about 100kHz) which caused this effect, were measured  in situ  over a wide temperature range during the quasi-static deformation of single crystals. An increase in the efficiency of the ultrasonic effect upon plastic deformation was observed with increasing temperature. The data provided evidence of a distinction between the basic mechanisms of the acoustoplastic effect and of the amplitude-dependent internal friction. The absorption of ultrasound was due largely to dislocation/point-defect interactions under the reversible movement of mobile dislocations. A mechanical activation of the irreversible movement of a mobile dislocation through the long-range internal stress fields of other dislocations and dislocation pile-ups was suggested to be the basic mechanism of the acoustoplastic effect. Mechanisms were considered which might govern the temperature dependences of the acoustoplastic effect, amplitude-dependent internal friction and an amplitude hysteresis of the internal friction.

Effect of Temperature on the Amplitude Dependences of the Acoustoplastic Effect and Internal Friction during Deformation of Crystals K.V.Sapozhnikov, S.B.Kustov: Philosophical Magazine A, 1997, 76[6], 1153-68