On the nature of acoustic emission and internal friction during cyclic deformation of metals

A strong correlation between acoustic emission (AE) and internal friction (IF) has been established experimentally during rapid hardening of model copper polycrystals and single crystals deformed cyclically at constant plastic strain amplitudes. The difference between these two interrelated phenomena becomes pronounced when strain localization occurs in persistent slip bands or deformation bands. We demonstrate that the extension of the Kocks-Mecking-Estrin constitutive modelling approach to the cyclic deformation mode allows calculation of the major characteristics of both IF and AE in the same universal dislocation-based phenomenological framework, highlighting the fundamentally similar nature of both phenomena originating from elastic energy dissipation during plastic deformation.