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 fiction (ADIF) and to a comparison between the macroyield stress c, and microyield stress G, evaluated &om 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 q(T) and o,(T) has been demonstrated. Deviations &om the similarity law can be used for analysis of the low and high temperature anomalies of cc(T). The thermal vibrations of atoms rather than the thermal fluctuations are concluded to be responsible for the yield stress temperature dependence.