This paper focuses on local probe Auger spectroscopy studies of segregation and oxidation of in situ fractured Ni3Al specimens, both with and without B-doping. Although immediately after in situ fracture small amounts of segregated B at grain boundaries were observed occasionally in the B-doped specimens, the amount of B at the intergranular fracture surface drastically increased with time upon exposure to the ambient vacuum. After subsequent removal of B by depth profiling by in situ Ar+-bombardment (1 keV) at a rate of ~3.3 nm/min, B again segregated to the surface within several hours, accompanied by surface oxidation, under ultrahigh vacuum conditions at room temperature. Possible mechanisms of B surface segregation are related to the high binding energy between B and O and the fact that B lowers the surface energy of a Ni-enriched surface. Finally, prolonged exposure of the fracture surface to the electron beam is shown to lead to enhanced Ni oxidation and to less B surface segregation.
|Pagina's (van-tot)||254 - 259|
|Nummer van het tijdschrift||3|
|Status||Published - 2001|
|Evenement||19th European Conference on Surface Science (ECOSS-19) - , Spain|
Duur: 5-sep-2000 → 8-sep-2000