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Microstructure evolution in L12 hardened Co-base superalloys during creep

Published online by Cambridge University Press:  18 September 2017

Yuzhi Li
Affiliation:
School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China
Florian Pyczak*
Affiliation:
Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Geesthacht 21502, Germany
Jonathan Paul
Affiliation:
Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Geesthacht 21502, Germany
Michael Oehring
Affiliation:
Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Geesthacht 21502, Germany
Uwe Lorenz
Affiliation:
Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Geesthacht 21502, Germany
Zekun Yao
Affiliation:
School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China
*
a) Address all correspondence to this author. e-mail: florian.pyczak@hzg.de
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Abstract

The plastic deformation mechanisms and the microstructure development during creep deformation of L12-hardened Co-base superalloys show a number of unique features. The preferred orientation of rafting is determined by their positive lattice mismatch. In addition, the regular interfacial dislocation networks often found in rafted specimens of other types of superalloys do not form. While the ordered γ′-L12 precipitates are supposed to harden the material, they are actually found to be frequently cut by partial dislocations generating stacking faults. In this work, specimens from creep tests interrupted at different strains were investigated using transmission and scanning electron microscopy. By this, it is possible to find out which of these processes take place in which stage of creep deformation. For a better understanding of creep deformation, the balance between γ′ cutting and dislocation activity within the matrix channels is of special interest.

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Articles
Copyright
Copyright © Materials Research Society 2017 

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Footnotes

Contributing Editor: Mathias Göken

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Microstructure evolution in L12 hardened Co-base superalloys during creep
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