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High-temperature oxidation of CoGa: Influence of the crystallographic orientation on the oxidation rate

Published online by Cambridge University Press:  31 January 2011

U. Koops
Affiliation:
Institute of Physical Chemistry, Darmstadt University of Technology, Petersenstraβe 20, D–64287 Darmstadt, Germany
D. Hesse
Affiliation:
Max Planck Institute of Microstructure Physics, Weinberg 2, D–06120 Halle, Germany
M. Martin
Affiliation:
Institute of Physical Chemistry I, Aachen University of Technology (RWTH), Templergraben 59, D–52056 Aachen, Germany
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Abstract

The crystallographic orientation plays an important role in high-temperature oxidation of the intermetallic compound CoGa. When CoGa is exposed to air at elevated temperatures, the oxide β–Ga2O3 is formed, and different scale growth rates are observed, depending on the crystallographic orientation of the CoGa grains. This dependence is a consequence of the anisotropy of the gallium diffusion rate through the β–Ga2O3 scale and of a topotaxial orientation relationship occurring between β–Ga2O3 and CoGa. The combination of ex situ techniques, such as transmission electron microscopy and electron backscatter diffraction with optical microscopy, applied in situ resulted in a thorough understanding of these relations and of the oxidation process in general.

Type
Articles
Copyright
Copyright © Materials Research Society 2002

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References

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