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On the Pre‐Exponential Factor in the Rate Equation for Plastic Flow
Author(s) -
Sueek T.,
Luton M. J.,
Jonas J. J.
Publication year - 1973
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.2220570222
Subject(s) - exponential function , thermodynamics , materials science , plasticity , zirconium , shear modulus , yield (engineering) , modulus , mathematics , mechanics , physics , mathematical analysis , composite material , metallurgy
Although it is not generally possible to calculate the pre‐exponential factor ϵ 0 directly from experimental results, the assumption that the obstacle‐dislocation interaction has the same temperature dependence as the shear modulus permits ϵ 0 to be determined from the available data. An iterative procedure is described which, when convergent, is consistent with the thermodynamic properties of such obstacles. The approach is applied to high temperature yield data for zirconium and the results are compared with various physical models for the pre‐exponential term. The values of the activation parameters and their dependence on stress and temperature are consistent with the interpretation that the rate controlling process in the high temperature yielding of zirconium is the unpinning of the nodes associated with a specific group of segment lengths selected from the total segment length distribution present within the material.