The free energy of a pinned dislocation

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Abstract
The free energy of a dislocation containing a number of mobile pinning points constrained to move within the dislocation core has been determined. An equilibrium distribution of pinning points then is obtained by minimizing the Helmholtz free energy with respect to the location of the points. It is found that this distribution is sensitive to the magnitude of an externally applied stress. For a small applied stress the effect of entropy cannot be overcome and the distribution of pinning points is unaffected. When a critical stress level is reached, however, the pinning points redistribute along the dislocation line until a balance is attained between potential energy and entropy. Various manifestations of dislocation theory such as microcreep, internal friction and binding energies are discussed in light of the present results.