NONLINEAR MECHANICAL RELAXATION ASSOCIATED WITH DISLOCATION-POINT DEFECT INTERACTION

The concept of nonlinear anelasticity is proposed to denote that prope rty of solids in virtue of which mechanical relaxation is acompanied b y nonlinear relationship between stress and strain, so that a strong a mplitude effect appears even under low stress levels. Seven internal f riction peaks (vs. temperature) were observed in cold-worked and parti ally annealed aluminium containing copper or magnesium solute atoms. T hese peaks exhibit nonlinear anelastic behaviour manifested by the app earance of normal and anomalous amplitude effect within the temperatur e range of these peaks. The origin of these seven peaks was attributed to the short-ranged or long-ranged diffusion of the solute atoms (sin gle or complex) caused by their interaction with dislocation kinks. A unified ''dislocation kink-solute atom atmosphere'' model in correlati on with a ''following, dragging, breaking away'' relaxation process wa s suggested for these seven peaks so that the specific explanations fo r each peak are self-consistent and support each other.