Interactions of point defects with dislocations in silver chloride crystals

Internal friction techniques at 35 kHz were used to study the interactions between point defects and dislocations in crystals of silver chloride. The Granato-Lücke plots of the amplitude-dependent decrement were not linear, but were concave upward. Various analyses of these data all gave pin-dislocation binding energies of approximately 0·2 eV. An extensive study was made of the decay of the amplitude-independent decrement after “excitation” by high-amplitude oscillation; the Granato-Lücke L⁴ law was found valid, but the arrival of pins proceeded as t^1/3, rather than the usual t^2/3 found in deformed specimens. A first-order model of the response of a slightly perturbed Maxwell atmosphere about the dislocation is presented. The model quantitatively describes the experimental results. The activation energy of the rate constant was found to be 0·42 eV, consistent with data on solute diffusion and strain-aging.