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Electron Microscopy Studies of the High Temperature Oxidation Behavior of NiAl

Published online by Cambridge University Press:  10 February 2011

J. C. Yang
Affiliation:
Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801
E. Schumann
Affiliation:
Max-Planck-Institut für Metallforschung, Stuttgart, D-70174, GERMANY
I. Levin
Affiliation:
Department of Materials Engineering, Technion, Haifa, 32000, ISRAEL
H. Muellejans
Affiliation:
Max-Planck-Institut für Metallforschung, Stuttgart, D-70174, GERMANY
M. Ruhle
Affiliation:
Max-Planck-Institut für Metallforschung, Stuttgart, D-70174, GERMANY
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Abstract

The transient oxidation stage of single crystal (001)NiAl was investigated using scanning electron microscopy, transmission electron microscopy, electron diffraction, high resolution electron microscopy and electron energy loss spectroscopy (EELS). (001)NiAl was oxidized in air at 950°C in order to produce transient forms of alumina on the surface. After oxidation, an oxide scale with plate-like surface morphology formed. We found that the main transient alumina polymorph is γ-Al2O3. The platelets which formed on the surface of the oxide are most likely α-A12O3, not θ-Al2O3. Randomly-oriented α-Al2O3 grains were observed at the oxide/metal interface. The NiAl/γ-Al2O3 interfaces were examined with EELS. From the changes observed in the electron energy loss spectra, the interfacial terminating plane is determined. Lattice matching arguments are given to explain why these terminating planes are energetically favorable.

Type
Research Article
Copyright
Copyright © Materials Research Society 1997

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References

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