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An Analysis of the Entropy of Thermally Activated Dislocation Motion Based on the Theory of Thermoelasticity
Author(s) -
Dimelfi R. J.,
Nix W. D.,
Barnett D. M.,
Holbrook J. H.,
Pound G. M.
Publication year - 1976
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220750221
Subject(s) - isotropy , linear elasticity , elasticity (physics) , dislocation , entropy (arrow of time) , anisotropy , classical mechanics , hydrostatic equilibrium , materials science , mathematical analysis , mechanics , mathematics , physics , thermodynamics , condensed matter physics , quantum mechanics , finite element method
An analysis is made of the entropy of thermally activated dislocation motion using the continuum theory of thermoelasticity. A relation for the activation entropy, which is valid for non‐linear, anisotropic elastic solids is derived. The activation entropy is expressed in terms of the general stress state in the solid and is found to be linear in the first temperature derivative of the elastic compliances, a relation often applied to the special case of linear, isotropic elasticity, but not previously derived for the more general case treated here. It is shown that, under the special conditions where pure shear or pure hydrostatic stress states are associated with both the initial and activated states, the present result can be reduced to the one often found in the past for the case of linear isotropic elasticity. However, these special conditions are never satisfied either in the thermally activated motion of dislocations or in diffusion. This suggests that the previous result is not applicable to these situations.