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Low-cycle fatigue of single crystal nickel-based superalloy – mechanical testing and TEM characterisation

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posted on 04.01.2019 by Lu Zhang, Liguo Zhao, Anish Roy, Vadim Silberschmidt, G. McColvin
Low-cycle fatigue (LCF) is studied for a nickel-based single-crystal superalloy in this paper, with a focus on the effect of crystal orientation and temperature. Specifically, cyclic deformation of the alloy was compared for [001]- and [111]-oriented samples tested under strain-controlled conditions at room temperature and 825 °C. Either cyclic hardening or softening was observed during the LCF process, depending on the strain amplitude, crystallographic orientation and temperature. LCF life was also reduced significantly by changing loading orientation from [001] to [111] or increasing temperature to 825 °C. Employing a comprehensive study with transmission electron microscopy (TEM), a connection between microstructure and mechanical behaviour of the alloy is discussed. It was found that the processes of γ′-precipitate dissolution and dislocation recovery were responsible for cyclic softening. Alignments and pile-ups of dislocations in the γ matrix, which prohibited their movement and reduced the interaction of dislocations on different slip systems, contributed to cyclic hardening.

Funding

This work was funded by the EPSRC (Grant EP/M000966/1 and EP/K026844/1) of the UK and in collaboration with GE Power, Rolls-Royce and dstl.

History

School

  • Mechanical, Electrical and Manufacturing Engineering

Published in

Materials Science and Engineering: A

Citation

ZHANG, L. ... et al., 2019. Low-cycle fatigue of single crystal nickel-based superalloy – mechanical testing and TEM characterisation. Materials Science and Engineering: A, 744, pp. 538-547.

Publisher

© 2018 The Author(s). Published by Elsevier B.V.

Version

VoR (Version of Record)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) licence. Full details of this licence are available at: http://creativecommons.org/licenses/ by/4.0/

Acceptance date

17/12/2018

Publication date

2018-12-18

Notes

This is an open access article under the CC BY license (http://creativecommons.org/licenses/BY/4.0/).

ISSN

0921-5093

Language

en

Licence

Exports