High temperature scaling of two-phase Fe-Cu alloys under low oxygen pressures

Citation
Y. Niu et al., High temperature scaling of two-phase Fe-Cu alloys under low oxygen pressures, CORROS SCI, 42(1), 2000, pp. 165-181
Citations number
45
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Material Science & Engineering
Journal title
CORROSION SCIENCE
ISSN journal
0010-938X → ACNP
Volume
42
Issue
1
Year of publication
2000
Pages
165 - 181
Database
ISI
SICI code
0010-938X(200001)42:1<165:HTSOTF>2.0.ZU;2-P
Abstract
The oxidation of binary two-phase Fe-Cu alloys containing 25, 50 and 75 wt% Cu and composed of mixtures of the two terminal solid solutions of copper in iron and iron in copper has been studied at 800-900 degrees C under oxyg en pressures below the stability of copper oxides. The oxidation followed t he parabolic law only in some cases, while in others it was rather irregula r. The scaling rates of the alloys were lower than for pure iron and decrea sed with an increase in the copper content under constant temperature. The scales were always composed of an inner layer containing a mixture of coppe r metal and iron oxide and of an outer layer of iron oxide with very little dissolved copper. The interface between the two layers was generally regul ar and corresponded approximately to the location of the original alloys su rface, while the distribution of the two phases in the mixed region followe d closely that of the two metal phases in the original alloys. No significa nt iron depletion was observed in the alloys beneath the region of internal oxidation. The peculiar scale microstructures observed for these alloys ar e mainly a result of the limited mutual solubility of the two components an d of their special microstructures involving the presence of two phases of widely different composition. (C) 1999 Elsevier Science Ltd. All rights res erved.