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Interfacial Solute-Atom Segregation: An Atomic-scale Ahenomenon with Implications for the Oxidation Kinetics of Pt-Al Alloys

Published online by Cambridge University Press:  02 July 2020

E.C. Dickey ,
K.B. Alexander  and
B.A. Pint
E.C. Dickey
Affiliation:
Dept. of Chemical and Materials Engineering, University of Kentucky, Lexington, KY40506-0046
K.B. Alexander
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN37831.
B.A. Pint
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN37831.
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Extract

Interfacial solute-atom segregation is known to have profound effects on macroscopic physical properties (e.g. electronic transport or fracture toughness) in interface-influenced or controlled materials. It has recently been shown that solute-atom segregation also can play an influential role in the dynamics of phase transformations, in particular the oxidation kinetics of alumina-forming alloys such as PtAl. By coupling analytical electron microscopy (AEM) with conventional macroscopic oxidation studies, we have demonstrated that oxidation kinetics are affected by atomic-scale segregation of dopant species to the grain boundaries and metal-oxide boundaries in the system. Furthermore, these studies illustrate the utility of AEM techniques in elucidating the atomic-scale aspects of macroscopic physical phenomena such as phase transformations.

Oxidation studies were carried out on PtAl alloys with and without small additions of Zr to the alloy. While the pure PtAl alloys exhibited oxide scale spallation and very fast oxidation rates, the Zrcontaining alloys maintained a well-adhered oxide scale and significantly lower oxidation rates.

Type
Spatially-Resolved Characterization of Interfaces in Materials
Information
Microscopy and Microanalysis , Volume 4 , Issue S2: Proceedings: Microscopy & Microanalysis '98, Microscopy Society of America 56th Annual Meeting, Microbeam Analysis Society 32nd Annual Meeting, Atlanta, Georgia July 12-16, 1998 , July 1998 , pp. 770 - 771
Copyright
Copyright © Microscopy Society of America

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References

References:

1.Dickey, E.C., Pint, B.A.,Alexander, K.B., Wright, I. G., in High Temperature Surface Engineering, ed. J. Nicholls, in press.Google Scholar
This research was sponsored by the U.S. Department of Energy, Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Industrial Technologies, as part of the Advanced Turbine Systems Program and by the Division of Materials Sciences under contract DE-AC05-96OR22464 with Lockheed Martin Energy Research Corp.Google Scholar