Application of Internal Friction to Analysis of Plastic Behaviour of Crystals

A relationship between dislocation internal friction, microplastic and macroplastic behaviour of crystals has been considered. Main attention has been paid to the shape of the dislocation hysteresis responsible for the amplitude-dependent internal friction (ADIF) and to a comparison between the macroyield stress σc and microyield stress σe evaluated from the ADIF. It is shown that the same functional form of the ADIF curve may be due to different types of the dislocation hysteresis loop. A proportionality (similarity law) between the temperature dependences σc(T) and σe(T) has been demonstrated. Deviations from the similarity law can be used for analysis of the low and high temperature anomalies of σc(T). The thermal vibrations of atoms rather than the thermal fluctuations are concluded to be responsible for the yield stress temperature dependence