Non-linear anelasticity due to dislocation-solute atom interactions in solid solutions

A theory for the non-linear, strain-amplitude-dependent internal friction (ADIF) in solid solutions due to dislocation-solute atom interactions has been developed. The suggested model accounts for different modes of dislocation-solute atom interactions: solute atoms, distributed in the dislocation glide plane, represent short-range obstacles for the dislocation motion; solute atoms, situated away from the dislocation glide plane, create diffuse weak long-range elastic stress fields, also impeding dislocation motion. Dislocations overcome localised obstacles under the combined action of the applied stress and thermal energy, whereas diffuse long-range obstacles can be surmounted only athermally. Numerical calculations of the ADIF, strain-amplitude-dependent modulus defect, their ratio, and of the fraction of the athermal ADIF component have been performed. The model predicts a complicated multistage behaviour of the parameters of the non-linear anelasticity in the strain amplitude-temperature-solute concentration domain which is in excellent agreement with recent experimental data. (C) 2000 Elsevier Science S.A. All rights reserved.