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Abstract
In recent years, segregation to a variety of sinks has been observed in a wide range of alloys during irradiation. There have also been a number of theoretical calculations of the segregation to free surfaces in both dilute and concentrated alloys. In this paper, we show that the boundary conditions used have a strong effect on the calculated solute concentration profiles. In most calculations the free surface is assumed to be an ideal sink for vacancies and interstitials, and the calculated solute concentration profiles are very steep close to the free surface. In this paper, we examine the physically more realistic case of rate-limitation boundary conditions for the absorption of vacancies and interstitials at the free surface and show that this reduces considerably the solute concentration gradients close to the surface. We also discuss the implications of this behaviour for the modelling of experimental results of solute segregation.