Kinetics of sulfur and phosphorus surface segregation competition in copper

Abstract

Surface segregation of impurities in metals may lead to significant enrichment in a monolayer. The segregation kinetics are usually described in terms of bulk diffusion; measurements of the segregation kinetics in single crystals have been used to determine the respective bulk diffusion coefficients. On the other hand, sulfur segregation in ferrous alloys has been reported to be accelerated via pipe diffusion. Moreover, segregation induced phase transitions may modify the segregation kinetics. The present paper deals with the kinetics of the segregation competition of sulfur and phosphorus in copper. On the basis of earlier measurements by Frech, a segregation model is developed, which takes into account bulk and pipe diffusion as well as structural phase transitions in the surface layer.