Surface segregation of antimony on ferritic single crystals

Antimony has frequently been reported to cause temper embrittlement induced by grain boundary segregation in steels containing both nickel and chromiu m. In order to study the interdependent segregation behaviour of antimony a nd nickel and the effect of chromium on segregation of these elements, surf ace segregation was studied on Fe-258 Cr-2%Ni-0.15%Sb and Fe-2.5%Si-2%Ni-0. 15%Sb single crystals. Segregation was investigated by means of Auger elect ron spectroscopy (AES) and low energy electron diffraction (LEED) in the te mperature range between 500 and 650 degrees C. On Fe-25%Cr-28Nt0.15%Sb. seg regation of antimony leading to surface saturation and cosegregation of nic kel are observed on (100), (110) and (111) oriented surfaces. LEED investig ations yield a complex domain structure which call be derived from a c(2 x 2) pattern for the (100) oriented surface and a (1 x 1) pattern for the (11 1) oriented surface. On the (110) oriented surface, reconstruction occurs. On Fe-2.5%Si-2%Ni-0.15%Sb, the investigated (100) oriented surface is also saturated with segregating antimony. Cosegregation of nickel occurs, but is weaiicr than on the crystal containing chromium; thus, chromium intensifie s cosegregation of nickel with antimony. The LEED pattern exhibits a comple x domain structure which is very similar to the structure observed on the ( 100) oriented surface of the crystal containing chromium. (C) 2000 Elsevier Science B.V. All rights reserved.