A diffusion process was proposed for the nucleation of a cavity at above half the melting point of a material, and under low applied tensile stresses where stress-assisted diffusion occurred. An equation was derived for the diffusion of N atoms into a bi-material boundary in order to begin nucleation. The stability of the solution of the equation was examined for a Cu/Al2O3 interface; resulting in an activation energy for boundary diffusion that was in excellent agreement with the typical values found for metals. An estimate of the time required for diffusion to create a small cavity was also obtained from the equation developed for nucleation. A mechanism was also developed for the supersaturation of vacancies that could result in final cavity formation. The amount of calculated supersaturation was within the range found in other studies. An incubation time before final stable cavitation was deduced, and was found to agree well with experimental data.

Transient Nucleation of Cavities under Coupled Lattice and Boundary Diffusion. C.M.Kennefick: Journal of Materials Science, 2004, 39[13], 4107-12