Abstract
The thermodynamics of cavity nucleation in solids subjected to external and internal stresses are analyzed. We show that the critical nucleus for cavity nucleation can be formed by alternative reversible work paths; either by condensation of pre-existing vacancies or by removal of atoms from the site of nucleation to sinks within the solid or at the surface. These two nucleation paths are shown to be equivalent, Strain energy terms which are quadratic in stress are found to arise in the free energy of the nucleus when relaxation of the void surface is taken into account. Two different cases of internally stressed solids are treated: one in which vacancy sources and sinks at the site of nucleation are locked and another in which vacancy sources and sinks are unlocked. In the former case the internal stress appears only quadratically or as crossterms in the formation free energy of the critical sized nucleus, while in the latter case, it appears in a linear term, additive to the applied stress, and has a strong effect on cavity nucleation. Problems involving complex nucleus shapes and the effects of plastic relaxation in cavity nucleation are also discussed.
Published Version
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