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In-situ SEM study of slip-controlled short-crack growth in single-crystal nickel superalloy

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journal contribution
posted on 13.11.2018 by Lu Zhang, Liguo Zhao, Anish Roy, Vadim Silberschmidt, G. McColvin
Initiation and growth of short cracks in a nickel-based single crystal were studied by carrying out in-situ fatigue experiments within a scanning electron microscope (SEM). Specimens with two different crystallographic orientations, i.e., [001] and [111], were tested under load-controlled tension fatigue in vacuum. Slip-caused crack initiation was identified at room temperature while initiation of a mode-I crack was observed at 650°C. Slip traces continuously developed ahead of the crack tip once initiated and acted as nuclei for early-stage crack growth at both room and high temperature (650°C). These slip traces were caused by accumulated shear deformation of activated octahedral slip systems, which were specifically identified by analysing the surface slip traces and crack-propagation planes. The crack-growth rates were evaluated against stress intensity factor range, revealing the anomaly of slip-controlled short-crack growth. The effects of crystallographic orientations and temperature on fatigue crack growth were subsequently analysed and discussed, including the influence of microstructural features such as carbides and pores.

Funding

The 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., 2018. In-situ SEM study of slip-controlled short-crack growth in single-crystal nickel superalloy. Materials Science and Engineering: A, 742, pp.564-572

Publisher

Elsevier (© the authors)

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

08/11/2018

Publication date

2018-11-09

Notes

This paper was published by Elsevier as Gold Open Access with a Creative Commons Attribution (CC BY 4.0) licence.

ISSN

0921-5093

Language

en

Licence

Exports