Issue |
MATEC Web of Conferences
Volume 14, 2014
EUROSUPERALLOYS 2014 – 2nd European Symposium on Superalloys and their Applications
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Article Number | 01001 | |
Number of page(s) | 6 | |
Section | Session 1: Alloy Development I: Ni-Based Alloys | |
DOI | https://doi.org/10.1051/matecconf/20141401001 | |
Published online | 29 August 2014 |
What is the role of rhenium in single crystal superalloys?
1 School of Metallurgy and Materials, University of Birmingham, Edgbaston B15 2TT, UK
2 Engineering Science Department, University of Oxford, Oxford OX1 3PJ, UK
3 Materials Department, University of Oxford, Oxford OX1 3PH, UK
a Corresponding author: a.mottura@bham.ac.uk
Rhenium plays a critical role in single-crystal superalloys –its addition to first generation alloys improves creep life by a factor of at least two, with further benefits for fatigue performance. Its use in alloys such as PWA1484, CMSX-4 and Rene N5 is now widespread, and many in this community regard Re as the “magic dust”. In this paper, the latest thinking concerning the origins of the “rhenium-effect” is presented. We start by reviewing the hypothesis that rhenium clusters represent barriers to dislocation motion. Recent atom probe tomography experiments have shown that Re may instead form a solid solution with Ni at low concentrations (< 7 at.%). Density functional theory calculations indicate that, in the solid solution, short range ordering of Re may be expected. Finally, Re has been shown to diffuse slowly in the γ-Ni phase. Calculations using a semi-analytical dislocation climb/glide model based upon the work of McLean and Dyson have been used to rationalise the composition-dependence of creep deformation in these materials. All evidence points to two important factors: (i) the preferred partitioning of Re to the γ phase, where dislocation activity preferentially occurs during the tertiary creep regime and (ii) a retardation effect on dislocation segments at γ/γ′ interfaces, which require non-conservative climb and thus an associated vacancy flux.
© Owned by the authors, published by EDP Sciences, 2014
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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