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O: Oberflächenphysik

O 9: Adsorption an Oberflächen (II)

O 9.5: Vortrag

Montag, 27. März 2000, 17:15–17:30, H37

Surface cosegregation of chromium and sulphur in single crystalline austenitic Fe-Ni-Cr alloys — •Christian Uebing¹, Jozef Janovec², Andrea Dziakova¹, and Elke Clauberg¹ — ¹Max-Planck-Institut f"ur Eisenforschung, D"usseldorf — ²Institute of Materials Research, Slovak Academy of Sciences, Kosice, Slovak Republic

In the present work we have studied cosegregation of sulphur and

chromium on well-defined austenitic Fe-Cr-Ni alloy surfaces. For this purpose we have investigated (100) oriented surfaces of

Fe-14.8%Cr-17.8%Ni (c_S = 9 wt-ppm) and

Fe-18%Cr-14%Ni (c_S = 18 wt-ppm) single crystals using Auger electron spectroscopy (AES) and low energy electron diffraction (LEED). Segregation experiments were carried out under UHV conditions at temperatures ranging from 500 to 900^∘C. Cosegregation of chromium and sulphur is well pronounced on the Fe-14.8%Cr-17.8%Ni(100) alloy surface, while on Fe-18%Cr-14%Ni(100) the surface concentration

of cosegregated chromium is rather small. On both surfaces sulphur segregation is characterized by a 2x2 LEED pattern. The results of the present study are compared with a previous study using ferritic Fe-15%Cr-S(100) alloy single crystals.