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Unpinning of Dislocations within the Framework of the Vibrating‐String Model
Author(s) -
Frank W.,
Frydman R.
Publication year - 1974
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.2220650114
Subject(s) - arrhenius equation , isothermal process , elasticity (physics) , dislocation , enthalpy , thermodynamics , string (physics) , physics , condensed matter physics , exponential function , mathematics , materials science , mathematical analysis , classical mechanics , theoretical physics , kinetics
Within the framework of the vibrating‐string model the frequency of thermally activated unpinning of dislocations from point obstacles is calculated with the aid of a dynamical theory. It is found that the unpinning frequency Γ has the form of an Arrhenius equation, Γ = Γ 0 e −Δ G/kT , where Δ G is the portion of the free enthalpy of activation which may be obtained by means of elasticity theory using isothermal elastic constants. The pre‐exponential factor Γ 0 is shown to decrease with increasing length of the pinned dislocation segments, contrary to the result obtained on the basis of the absolute rate theory.