The internal oxidation of two-phase binary alloys beneath an external scale of the less-stable oxide

Journal Article · Tue Apr 01 04:00:00 EST 1997 · Oxidation of Metals

DOI:https://doi.org/10.1007/BF01668518· OSTI ID:518362

Gesmundo, F; Viani, F ^[1]; Niu, Y ^[2]

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1. Universita di Genova (Italy)
2. Inst. of Corrosion and Protection of Metals, Shenyang (China)

The internal oxidation of two-phase binary A-B alloys by a single oxidant at high temperatures, under partial pressures sufficient to also form external scales of the less-stable oxide, is examined by means of quantitative models and compared with the corresponding behavior of single-phase alloys. It is shown that, depending on various factors, particularly on the solubility and diffusivity of the most-reactive component B in the most-noble component A, this process may or may not involve a diffusion process of the alloy components, leading to different scale morphologies. It is also concluded that even when the solubility and diffusivity of B in A are sufficiently high, so that the internal oxidation of the common type occurs, the restriction to the diffusion of B in the alloy due to its limited solubility affects the kinetics of internal oxidation, producing an increase of the rate of internal oxidation and of the critical concentration of B in the alloy required for the transition to the external oxidation of B with respect to single-phase alloys under the same values of all the relevant parameters. The lower the solubility of B in A, the larger these effects.

• Sponsoring Organization: USDOE
• OSTI ID: 518362
• Journal Information: Oxidation of Metals, Journal Name: Oxidation of Metals Journal Issue: 3-4 Vol. 47; ISSN OXMEAF; ISSN 0030-770X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BINARY ALLOY SYSTEMS
DIFFUSION
OXIDATION
SCALING
SOLUBILITY