Surface segregation on Fe-25 %Cr-2 %Ni-0.14%Sb-N,S (100) single crystal surfaces

Surface segregation on (100) oriented single crystal surfaces of the alloy Fe-25%Cr-2%Ni-0.14%Sb-N,S has been investigated by means of Auger electron spectroscopy (AES), low energy electron diffraction (LEED) and X-ray photoe lectron spectroscopy (XPS). The experiments have been carried out in the te mperature range from 500 degrees C to 700 degrees C in which a variety of s egregation phenomena is observed. In the low temperature range, cosegregati on of nitrogen and chromium occurs. Depth profiling and XPS studies suggest that the Cr and N segregation layer consists of (i) a two-dimensional surf ace compound and (ii) three-dimensional precipitates in the surface near re gion. A LEED investigation of the Cr and N saturated surface yields a clear (1 X 1) pattern after sufficiently long annealing times. At temperatures in excess of 600 degrees C, segregated nitrogen and chromiu m are replaced by segregating antimony and nickel. Studies of the kinetics show that nickel and antimony jointly enrich at the sample surface; this pr oves that true cosegregation occurs. An XPS study of the antimony and nicke l saturated surface shows that the antimony binding energy coincides with t he value that had been measured for the binding energy of segregated antimo ny on pure iron. The corresponding LEED pattern shows reflex splitting whic h indicates domain formation. A further increase of the temperature to about 700 degrees C causes segrega tion of sulphur displacing antimony from the surface. The sulphur covered s urface exhibits a typical c(2 X 2) LEED pattern. (C) 2000 Elsevier Science B.V. All rights reserved.