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High temperature properties and fatigue strength of novel wrought γ/γ′ Co-base superalloys

Published online by Cambridge University Press:  22 August 2017

Lisa Patricia Freund*
Affiliation:
Department of Materials Science and Engineering, Friedrich-Alexander Universität Erlangen-Nürnberg, Institute I, Erlangen 91058, Germany
Sven Giese
Affiliation:
Department of Materials Science and Engineering, Friedrich-Alexander Universität Erlangen-Nürnberg, Institute I, Erlangen 91058, Germany
Daniel Schwimmer
Affiliation:
Department of Materials Science and Engineering, Friedrich-Alexander Universität Erlangen-Nürnberg, Institute I, Erlangen 91058, Germany
Heinz Werner Höppel
Affiliation:
Department of Materials Science and Engineering, Friedrich-Alexander Universität Erlangen-Nürnberg, Institute I, Erlangen 91058, Germany
Steffen Neumeier
Affiliation:
Department of Materials Science and Engineering, Friedrich-Alexander Universität Erlangen-Nürnberg, Institute I, Erlangen 91058, Germany
Mathias Göken
Affiliation:
Department of Materials Science and Engineering, Friedrich-Alexander Universität Erlangen-Nürnberg, Institute I, Erlangen 91058, Germany
*
a)Address all correspondence to this author. e-mail: lisa.freund@fau.de
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Abstract

This paper presents the high temperature yield and fatigue strength as well as thermophysical properties of two polycrystalline wrought γ/γ′ Co-base superalloys developed for application in a temperature regime above 700 °C. The alloys CoWAlloy1 (Co42Ni32Cr12Al6W3Ti2.5Ta1.5 + Si,C,B,Zr,Hf) and CoWAlloy2 (Co41Ni32Cr12Al9W5 + Ti,Ta,Si,C,B,Zr,Hf) exhibited solidus temperatures of 1070 °C and 1030 °C, respectively, and a γ′ fraction of about 50%. CoWAlloy2 displayed a rather high Young’s modulus of 250 GPa. The two Co-base superalloys showed a good high temperature strength exceeding Ni-base disc alloys U720Li and Waspaloy at temperatures above 800 °C. When comparing the yield strength from tensile and compression tests, no asymmetry could be found. The low-cycle fatigue life of CoWAlloy2 at a total strain amplitude of 0.5% is similar to that of U720Li and Waspaloy (about 370 cycles, R = −1). During long-term aging for 1024 h at 750 °C, no additional phases were formed and the room temperature hardness barely changed.

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Articles
Copyright
Copyright © Materials Research Society 2017 

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Footnotes

b)

This author was an editor of this journal during the review and decision stage. For the JMR policy on review and publication of manuscripts authored by editors, please refer to http://www.mrs.org/editor-manuscripts/.

Contributing Editor: Yuntian Zhu

References

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