ESTIMATING THE SEGREGATION ENERGIES IN Cu BINARY SYSTEMS

The segregation energy of diluted species in a matrix can be calculated by first principles. These calculations are generally very computational demanding. The existing empirical models which use the difference in surface tensions to predict the segregation energy are limited, because they do not take the surface orientation of the matrix into account. In this investigation a model was developed which can estimate the segregation energies of segregating species in a binary system. The model makes use of the sublimation energies and takes the orientation of the surface into account. The model shows that the driving force for segregation is not the difference in surface tensions (between the surface tension of the pure element and the surface tension of the element in the alloy) but the difference in surface energies. The results of the calculations were used to simulate the Ag and Sb segregation to the (111) surface of copper.