The Surface Tension of Binary Alloys: Simple Models for Complex Phenomena

Surface segregation is the key to understanding the surface tension γ of alloys. The basic phenomena can be demonstrated qualitatively by using the ideal solution model. For a binary system, this model is first used to explain the temperature dependence of the surface tension. A simple criterion is established for sign reversal of the temperature coefficient. The ideal solution model is then extended to include the effect of compound formation. A simple explicit equation is proposed which fits existing data surprisingly well.