SURFACE SEGREGATION - COMPARISON OF MODELS AND RESULTS

It is well established that the surface composition of a metal alloy may differ markedly from that of the bulk. Theoretical treatments of this phenomenon have been mostly based on models for regular or related solutions. Experimentalists have reported a large body of surface composition data, mostly from the electron spectroscopies. Comparison of these results with the predictions of the models is appropriate to indicate potentially fruitful directions for future work. Though general agreement between theory and experiment is good, quantitative correlation has been hampered by inadequate model calculations, clouded experimentation, and difficult-to-interpret experimental results. Extension of the quasichemical model and inclusion of strain effects improves correlations with previously reported data. Comparing the results of such improved calculations with the sampling capability of surface elemental analysis techniques shows that the relationship between the two is not simple and can be fully elucidated only in some instances. © 1979.