AN EXPERIMENTAL AND THEORETICAL-STUDY OF SURFACE SEGREGATION IN A FE-6AT.PERCENT-SI BICRYSTAL

The analysis of segregation phenomena in bicrystals is an important st ep for the understanding of combined effects of the elementary diffusi on processes involved in the segregation in polycristalline systems. T he segregation of Si and P in a Fe-6at.%Si bicrystal with a (100) and (110) surface has been investigated by means of AES (Anger electron sp ectroscopy). For these experiments the technique of a linearly increas ed temperature has been applied. Significant differences between the s egregation kinetics at the two surfaces of the sample have been found on the one hand for the maximum coverage of P and on the other hand fo r the high temperature behaviour of Si. Additionally, model calculatio ns based on the KTBIM (kinetic tight binding Ising model) have been pe rformed to qualitatively describe the experimental results. It is show n, that the striking differences between the segregation behaviour at the two differently oriented surfaces can be explained by different se gregation energies of P, whereas Si plays a minor role due to its rela tively small segregation energy.