The Oxide Scale Growth Mechanism on Fe20Cr5Al+RE Alloy in SO2+O2

Abstract:

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The oxidation mechanism of FeCrAl (+RE), RE: reactive elements: Y and Hf) thin foils was studied at temperatures ranging from 1093 K to 1173 K in SO2+1%O2 atmosphere. Materials were subjected to isothermal and thermal cycling exposures as well as to the so-called two-stage-oxidation. In the latter, an oxygen isotope 18O2 was used as a tracer. Starting materials and scales were characterized using Grazing Angle X-Ray Diffraction (GA-XRD), EDX, SEM, XPS and High Spatial Resolution Secondary Ion Mass Spectrometry (HSR-SIMS). The obtained results showed within the studied range of exposure conditions the scales on all the studied alloys grow via outward mechanism typical for transient oxides and not for the -Al2O3 which is consistent with phase composition results and scale morphology and/or microstructure. It was also found that ‘as received’ foils are not bare metals but complex oxide-on-metal systems resulting from their manufacturing procedure. The obtained results are discussed in terms of the diffusion-related transport properties of the scale and of the scale phase composition.

Info:

Periodical:

Defect and Diffusion Forum (Volumes 289-292)

Edited by:

A. Agüero, J.M. Albella, M.P. Hierro, J. Phillibert and F.J. Pérez Trujillo

Pages:

541-550

DOI:

10.4028/www.scientific.net/DDF.289-292.541

Citation:

J. Jedlinski et al., "The Oxide Scale Growth Mechanism on Fe20Cr5Al+RE Alloy in SO2+O2", Defect and Diffusion Forum, Vols. 289-292, pp. 541-550, 2009

Online since:

April 2009

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$35.00

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