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Changes in Crystal Structure and Microhardness During Thermal Treatment of a NiCoCrAlY Alloy.

Published online by Cambridge University Press:  17 March 2011

Thomas Rehfeldt ,
Gerhard Schumacher  and
Hellmuth Klingelhoeffer
Thomas Rehfeldt
Affiliation:
Hahn-Meitner-Institut Berlin GmbH, Glienicker Strasse 100, D-14109 Berlin, Germany
Gerhard Schumacher
Affiliation:
Bundesanstalt fuer Materialforschung und -pruefung, Unter den Eichen 87, D-12205 Berlin, Germany
Hellmuth Klingelhoeffer
Affiliation:
Bundesanstalt fuer Materialforschung und -pruefung, Unter den Eichen 87, D-12205 Berlin, Germany
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Abstract

The stability of microstructure and the microhardness of a NiCoCrAlY alloy was studied after thermal treatment at high temperatures and subsequent quenching into ice water. The alloy revealed mainly two ordered phases, a γ' phase with L12 crystal structure and a β phase with B2 structure. The γ' phase is shown to become unstable in the temperature range between 1073 K and 1373 K where it undergoes an order-disorder phase transformation. The low transformation temperature compared to pure Ni3Al is ascribed to deviations from the Ni3Al stoichiometry and to the additional alloying elements Co and Cr. The γ'-γ order-disorder transformation is shown to be attended by a decrease in microhardness of about 30 %.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 645: Symposium M – Thermal Barrier Coatings-2000 , 2000 , M9.13.1
Copyright
Copyright © Materials Research Society 2001

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References

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