Surface segregation on Fe-25%Cr-2%Ni-0.1%Sb single crystals

Surface segregation of various segregating species has been investigated on Fe-25%Cr-2%Nd-0.1%Sb-N single crystals by AES and LEED. The experiments we re performed on (100) oriented surfaces in the temperature range between 45 0 degrees C and 650 degrees C. At temperatures up to 500 degrees C, cosegre gation of nitrogen and chromium is observed; the resulting CrN surface comp ound exhibits a characteristic (1 x 1) LEED pattern. For higher temperature s, antimony segregates to the surface accompanied by nickel, and replaces n itrogen and a large part of the chromium. This displacement process is reve rsible. The kinetics of the replacement of CrN by antimony and nickel depen d on the pretreatment of the sample. A depth profile of the segregation lay er of antimony and nickel shows that the enrichment of these elements is re stricted to one monolayer. A surface covered by antimony and nickel yields a complex LEED pattern that is related to an imperfect c(2 x 2) structure. (C) 1999 Elsevier Science B.V. All rights reserved.