A model study of displacement instabilities during cyclic oxidation

The shape changes that occur at imperfections on the surface of an alumina-forming alloy, subject to thermal cycling, have been simulated and measured. Observations have been made by emplacing a surface groove into a FeCrAlY material. Upon thermal cycling, large shape distortions have been observed:...

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Bibliographic Details
Published in:Acta materialia 2002-04, Vol.50 (6), p.1263-1273
Main Authors: Karlsson, A.M., Levi, C.G., Evans, A.G.
Format: Article
Language:English
Subjects:
Applied sciences
Exact sciences and technology
Metallurgical fundamentals
Metals. Metallurgy
Multilayers
Oxidation
Production of metals
Thermal cycling
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Summary:The shape changes that occur at imperfections on the surface of an alumina-forming alloy, subject to thermal cycling, have been simulated and measured. Observations have been made by emplacing a surface groove into a FeCrAlY material. Upon thermal cycling, large shape distortions have been observed: whereas, for comparable isothermal oxidation, the shape changes are minimal. The simulations predict similar responses. Upon cycling, upward displacements (pile-up) occur around the perimeter, accompanied by downward displacements at the center. Yet, minimal displacements arise upon isothermal oxidation. To realize cyclic displacements comparable in magnitude to those found experimentally, large values of the in-plane growth strain are required and the bond coat must be relatively soft.
ISSN:1359-6454
1873-2453
DOI:10.1016/S1359-6454(01)00403-7