Efficiency of vacancy annihilation at a surface and at dislocation loops in quenched aluminum

Abstract

The average efficiencies of dislocation loops and the surface as sinks for supersaturated vacancies in quenched aluminum at 40°C were measured using stereo electron microscopy. The growth of dislocation loops in the region adjacent to the surface was used to investigate the competition between the surface and the growing dislocation loops for the annihilation of vacancies. Comparing the spatial dependence of the fully grown loop size with the solution of the appropriate diffusion equation, the average efficiencies of both types of sinks were determined. The values of the efficiencies are \\ ̄ ge L = 0.9 ± 0.1 and \\ ̄ ge S = 0.7 ± 0.1 for dislocation loops and the surface, respectively. The results indicate that dislocation loops are quite good sinks during their growth at 40°C and that the aluminum surface, which is always covered by a protective and adhesive oxide layer, is not a perfect sink for vacancy annihilation.