Analyses on the Background of Dynamic Internal Friction and the Modulus Defect during Plastic Deformation

Abstract

An analysis on the background of dynamic internal friction (DIF) and the modulus defect (ΔG/G) at low frequency during plastic deformation in single crystal specimens is given. The background Q b -1 is considered to be associated with the string vibration of immobile dislocations under a combined action of a unidirectional stress and an alternating stress. It is shown that the frequency dependence of Q b -1 is different from that of the components associated with multiplication and long-range motion of mobile dislocations. Hence Q b -1 can be resolved from the total DIF with measurements of different frequencies. It is found that the resolved Q b -1 is not a constant as usually treated in the literature, but is variable with strain (or time). A detailed analysis shows that the variation of Q b -1 during deformation is associated with the variation of dislocation density. The variation of modulus defect ΔG/G during deformation is shown to be also associated with the variation of dislocation density.