Reaction Paths and Activation Energies for Dislocation Unpinning
作者:
L. J. Teutonico,
K. Lücke,
F. W. Heuser,
A. V. Granato,
期刊:
The Journal of the Acoustical Society of America
(AIP Available online 1969)
卷期:
Volume 45,
issue 6
页码: 1402-1416
ISSN:0001-4966
年代: 1969
DOI:10.1121/1.1911618
出版商: Acoustical Society of America
数据来源: AIP
摘要:
For the purpose of developing a theory of thermally assisted amplitude dependent damping, the equilibrium configurations and activation energies of pinned dislocations are calculated. The model is of a dislocation pinned by an arbitrary number of equidistant pinning points of equal strength. New features not found for a simple double loop are obtained, but most of the important physical processes for the general case are already obtained for a triple loop. The more important of these features are: (i) There are intermediate energy minima between the pinned state and the broken‐away state; (ii) for a given stress more than one reaction path between the pinned state and the broken‐away state may exist; (iii) multiple‐pin breakaway can occur by a single activation; (iv) thermal breakaway can occur at smaller loop lengths or at smaller stresses than is the case for a single pin. A discussion is given of the possible reaction paths of the dislocation in the general (N‐loop) problem. It is shown which equilibrium configurations lie along the lowest reaction path. For the case of long loops, expressions are obtained for the activation energies for both breakaway and repinning along this reaction path.
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