Application of Internal Friction to Analysis of Plastic Behaviour of Crystals

Abstract
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 σ_c and microyield stress σ_e 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 σ_c(T) and σ_e(T) has been demonstrated. Deviations from the similarity law can be used for analysis of the low and high temperature anomalies of σ_c(T). The thermal vibrations of atoms rather than the thermal fluctuations are concluded to be responsible for the yield stress temperature dependence.