The oxidation of a Co-15 wt% yttrium alloy in 1 atm O-2 at 600-800 degreesC

Citation
Y. Niu et al., The oxidation of a Co-15 wt% yttrium alloy in 1 atm O-2 at 600-800 degreesC, INTERMETALL, 8(3), 2000, pp. 293-298
Citations number
31
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science","Material Science & Engineering
Journal title
INTERMETALLICS
ISSN journal
0966-9795 → ACNP
Volume
8
Issue
3
Year of publication
2000
Pages
293 - 298
Database
ISI
SICI code
0966-9795(200003)8:3<293:TOOACW>2.0.ZU;2-Z
Abstract
The oxidation of a cobalt-based alloy containing 15 wt% yttrium (Y) as well as of pure yttrium has been studied in I arm of pure oxygen at 600-800 deg rees C. The alloy always corrodes faster than pure cobalt and follows the p arabolic rate law only approximately, forming an external scale of cobalt o xide which in its inner section contains particles of yttrium oxide. Beneat h the external scales, a region of internal oxidation of yttrium having a d epth much larger than predicted using the known solubility and diffusivity of oxygen in pure cobalt is also present. This anomalous depth is attribute d to enhanced oxygen diffusion in the alloy along preferential paths associ ated with the localized internal oxidation of yttrium. No yttrium depletion is observed in the alloy beneath the front of internal oxidation. The scal ing behavior of this alloy is interpreted by taking into account the limite d solubility of yttrium in cobalt and the presence of the intermetallic com pound Co-17 Y-2. (C) 2000 Elsevier Science Ltd. All rights reserved.