Numéro |
J. Phys. IV France
Volume 03, Numéro C9, Décembre 1993
Proceedings of the 3rd International Symposium on High Temperature Corrosion and Protection of MaterialsActes du 3ème Colloque International sur la Corrosion et la Protection des Matériaux à Haute Température |
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Page(s) | C9-385 - C9-393 | |
DOI | https://doi.org/10.1051/jp4:1993940 |
Actes du 3ème Colloque International sur la Corrosion et la Protection des Matériaux à Haute Température
J. Phys. IV France 03 (1993) C9-385-C9-393
DOI: 10.1051/jp4:1993940
Accelerated oxidation of aluminides at intermediate temperatures
H.J. Grabke, M.W. Brumm, M. Steinhorst and B. WagemannMax-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany
Abstract
The aluminides NbAl3 and NiAl may show accelerated oxidation in a range of
intermediate temperatures 600-1000 °C, especially at reduced oxygen pressures. Such pressures
in the range 10-2 to 10-30 bar O2 have been established for exposures in ampoules with
the specimens, by enclosing also buffer mixtures such as Cu-Cu2O, Fe3O4-Fe2O3, Ni-NiO etc.
NbAl3 disintegrates into small particles (pesting) and NiAl shows internal oxidation, general or
localized, and oxidation along grain boundaries. Auger analyses afier oxidation confirmed that
oxygen penetrates into grain boundaries of NbAl3 and NiAl. The transport of oxygen through
the outer oxide layer appears to be rate controlling, in the case of NbAl3 such transport is possible
through Nb2O5 in the scale and in the case of NiAl through other defects caused by insufficient
supply of oxygen in the exposures.
© EDP Sciences 1993