Surface segregation in alloys

We present a quasichemical theory to predict surface segregation in nonregular solutions. Surface concentration and surface short-range-order (SRO) parameters have been calculated for Ag-Au and Ag-Pd systems. Our results show segregation of Ag on the surface in both the systems. It is observed that the nonregular-solution model does not give results much different from the regular-solution model. However, the surface SRO parameters are significantly different from their bulk values. Surface concentrations averaged over the first few layers have also been calculated. Our results are in agreement with the results obtained from Auger electron spectroscopy