Surface segregation in alloys: Equilibrium segregation of Au to the (111) surface of Ni

Abstract

The experimental pitfalls in determining the equilibrium composition of an alloy surface are discussed. Among them are too‐slow bulk diffusion, surface evaporation, and contamination. These problems are illustrated with data on alloys containing less than 1% Au in Ni. We show that in the temperature range 800°–1000 °C, one can with care measure the equilibrium concentration of Au on the surface of the alloy using Auger spectroscopy. The heat of segregation of Au to the (111) surface of Ni has been obtained to be 12±2 kcal/mole.