Linear response analysis to gorsky relaxation of light interstitials in the presence of ordering

Abstract

Presents an understanding of how Gorsky relaxation (anelasticity caused by the diffusion of light solute interstitials under the influence of a stress gradient) is modified by the interactions between the solute atoms. Here use is made of a linear response formalism of anelasticity in which the strain response is expressed in terms of composition fluctuations of the solute atoms. These fluctuations are time dependent in view of the diffusion of the interstitial atoms. In order to compute this time dependence for the interacting interstitial system, a lattice-gas Hamiltonian is introduced and its kinetics treated within a mean-field-like approximation. Explicit expressions are derived for the anelastic strain, the relaxation strength, the frequency-dependent compliance and the internal friction, in terms of basic quantities like the interaction energy, the range of interaction, etc.