The thermal generation of vacancies from octahedral voids was studied by measuring the residual resistance due to vacancies which were generated during pulse-heating of the specimen for short times. The vacancy generation curves saturated at levels of 3.2δρ0 and 2.3δρ0, for voids with edge lengths of 6nm at 543 and 573K, respectively. Here, δρ0 was the resistivity due to the thermal equilibrium concentration of vacancies. In the case of voids with an edge length of 17nm, the generation curves saturated at a level of 1.02δρ0 to 1.05δρ0 for both temperatures. The results were consistent with a new model which took account of diffusion-limited vacancy generation from the edges and surfaces of the voids; with corresponding vacancy formation energies of E and ε. The new model yielded best-fit values of E = 0.1eV and ε = 0 for 6nm voids, and E = 0.04eV and ε = 0 for 17nm voids. The results indicated that the contribution which arose from the surface predominated for large voids, while the contribution arising from edges was more significant for small voids.

Thermal Generation of Vacancies from Voids in Aluminium. K.Ono, T.Kino: Philosophical Magazine A, 2001, 81[11], 2565-75