Christofidou, K.A. orcid.org/0000-0002-8064-5874, McAuliffe, T.P., Mignanelli, P.M. et al. (2 more authors) (2019) On the prediction and the formation of the sigma phase in CrMnCoFeNix high entropy alloys. Journal of Alloys and Compounds, 770. pp. 285-293. ISSN 0925-8388
Abstract
The almost limitless variations in potential compositions of high entropy alloys necessitates the use of computational methods when attempting to optimise for any given application. However, the accuracy of the current thermodynamic approaches commonly being used for this purpose remains under debate, as relatively few validatory studies have been performed. Within the CrMnFeCoNi family of alloys, the formation of the σ phase and how it is influenced by compositional variations is of particular interest for elevated temperature structural applications. Here, the role of Ni on the formation of the σ phase has been studied through a systematic series of CrMnFeCoNix alloys, 0 ≤ x ≤ 1.5, following 1000 h exposures at temperatures typically found to promote σ formation. Ni was found to have a significant effect on the phase stability of these alloys, suppressing the σ phase such that a single solid solution phase was the only stable phase in the CrMnFeCoNi1.5 alloy, whilst the CrMnFeCo alloy formed the σ phase during solidification. The corresponding thermodynamic predictions varied dramatically from the experimentally observed microstructures, indicating that the underlying databases require further optimisation. Interestingly, it was found that a relatively simple electronic structure based approach, New PhaComp, provided much more accurate predictions of the observed σ phase formation in the CrMnFeCoNix and CrMnxFeCoNi systems and could be manipulated to obtain σ formation temperatures. As such, this method could be extremely useful to those wanting to design CrMnFeCoNi high entropy alloys that are free from the σ phase.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2018 Elsevier. This is an author produced version of a paper subsequently published in Journal of Alloys and Compounds. Uploaded in accordance with the publisher's self-archiving policy. Article available under the terms of the CC-BY-NC-ND licence (https://creativecommons.org/licenses/by-nc-nd/4.0/). |
Keywords: | High entropy alloys; Phase diagrams; Phase transitions; Thermodynamic modelling |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Materials Science and Engineering (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 19 Sep 2019 14:26 |
Last Modified: | 19 Sep 2019 14:26 |
Status: | Published |
Publisher: | Elsevier |
Refereed: | Yes |
Identification Number: | 10.1016/j.jallcom.2018.08.032 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:151097 |