EDP Sciences Journals List
Issue J. Phys. IV France
Volume 03, Number C9, Décembre 1993
Proceedings of the 3rd International Symposium on High Temperature Corrosion and Protection of Materials
Actes du 3ème Colloque International sur la Corrosion et la Protection des Matériaux à Haute Température
Page(s) C9-231 - C9-240
DOI http://dx.doi.org/10.1051/jp4:1993921

Proceedings of the 3rd International Symposium on High Temperature Corrosion and Protection of Materials
Actes du 3ème Colloque International sur la Corrosion et la Protection des Matériaux à Haute Température

J. Phys. IV France 03 (1993) C9-231-C9-240

DOI: 10.1051/jp4:1993921

Effect of surface-applied reactive elements on the early stage oxidation of Fe- 18Cr-5Al and Fe-18Cr-5Al-1Hf alloys

P.Y. Hou1 and J. Stringer2

1  Materials Sciences Division, MS 62-203, Lawrence Berkeley Laboratory, Berkeley, CA 94720, U.S.A.
2  Electric Power Research Institute, Palo Alto, CA, U.S.A.


Abstract
The effect of lanthanum implantation on the early stage oxidation of Fe-18wt%Cr-5wt%Al and Fe-18wt%Cr-5wt%Al-1wt%Hf alloys at 1100 °C has been investigated. It was found that the reactive element enriched surfaces oxidized almost two times faster initially, and the scale that formed had a higher iron content. An extremely wavy scale/alloy interface developed in the early stage due to the accelerated growth and the change in scale composition. More scale separation was observed on the implanted surface of the Fe-Cr-Al alloy. Once separated, the alumina scale was free to grow laterally, and large growth buckles developed with oxidation time. The Hf-containing alloy did not show any scale separation regardless of the accelerated initial growth from lanthanum implantation. Sulfur was found everywhere at the scale/alloy interface on the Fe-Cr-Al alloy, but not on the Hf-containing alloy. These results suggest that for this alloy system, scale adhesion was dominated by a strong scale/alloy interface, and weakening of the interface may be caused by interfacial sulfur segregation.



© EDP Sciences 1993