Nonlinear Anelastic Internal Friction Associated with the Diffusion of Solute Atoms in Dislocation Cores

Recently, the activation energy associated with the anomalous internal friction peaks appearing in cold-worked Al-Cu and Al-Mg specimens around room temperature was found to be close to that associated to the pipe diffusion along dislocations. Consequently these internal friction peaks were attributed to the diffusion of Cu or Mg atoms in the dislocation core in aluminium and a physical model was suggested in terms of the dislocation kink model. The manifestations of these anomalous internal friction peaks conform to those predicted through a detailed mathematical analysis of the dislocation core diffusion by Winkler-Gniewek et al., in terms of the string model. This confirms further that the nonlinear anomalous internal friction peaks observed originate from dislocation core diffusion. In this paper, discussions are made on similarities and diversities of the string model and the kink model concerning this problem.