Abstract
Seal rings are installed for each turbine stage in gas turbine engines to minimize the loss in gas pressure and maintain engine efficiency. During service, seal rings become susceptible to failure by thermal fatigue as demonstrated by a case study. Therefore, a lower coefficient of thermal expansion is among the most important requirements for these applications. We show that long-range ordering in a Ni-Cr-Mo alloy can be used to synthesize a nanocrystalline intermetallic compound combining high strength, high ductility, low coefficient of thermal expansion, and an adequate oxidation resistance up to at least 700 °C. Twinning rather than slip is found to be the predominant deformation mechanism of the intermetallic compound, which is correlated with the crystallography of the disorder-to-order transformation and microstructure evolution. This could explain the enhanced plasticity of the intermetallic compound. The combination of enhanced plasticity, low-thermal expansion, and nano-sized crystals is expected to improve the resistance to thermal fatigue failure.
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References
H. Saracvanamuttoo, G. Rogers, and H. Cohen, Gas Turbine Theory, 6th ed., Pearson Education Ltd, Essex, 2009, p 445–450
M.P. Boyce, Gas Turbine Engineering Handbook, Elsevier, Oxford/Burlington, MA, 2006, p 549–553
D. Kay. Honeycomb Brazing Essentials for Successful Use as Turbine Seals Industrial Heating, November 1 Issue (2003)
R.W. Cahn, Intermetallics: New Physics, Contemp. Phys., 2001, 42(6), p 365–375
H.M. Tawancy, Long-Range Ordering: An Approach to Synthesize Nanoscale Superlattices with High Strength and High Ductility, Mater. Sci. Forum (2010), 633/634, p 421–435
K.A. Gschneidner et al., The Influence of Electronic Structure on the Ductile Behavior of B2 CsCl-Type Intermetallics, Acta Mater., 2009, 57, p 5876–5881
P.R. Swann, Dislocation Arrangements in Face-Centered Cubic Materials, Electron Microscopy and Strength of Crystals, G. Thomas and J. Washburn, Ed., Wiley, New York, 1963, p 131–181
H.M. Tawancy and M.O. Aboelfotoh, Experimental Observation of Transient Phases During Long-Range Ordering in a Ni-Mo Alloy, Phys. Stat. Solid. A Appl. Res., 1987, 99(2), p 461–466
H.M. Tawancy, Formation of DO22 Superlattice During Long-Range Ordering to Ni4Mo in a Ni-Mo Alloy, Scr. Met., 1984, 18(4), p 343–346
INCOLOY® Alloy 909, September 4, 2004, Publication Number SMC-077, Special Metals Corporation, Princeton, KY
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It is a pleasure to acknowledge the continued support of King Fahd University of Petroleum & Minerals as well as the Saudi Ministry of Higher Education.
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Tawancy, H.M., Al-Hadhrami, L.M. A Nanocrystalline Ni2(Cr,Mo) Intermetallic with Potentially Useful Combination of Properties for Gas Turbine Seal Ring Applications. J. of Materi Eng and Perform 21, 1374–1379 (2012). https://doi.org/10.1007/s11665-011-0010-5
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DOI: https://doi.org/10.1007/s11665-011-0010-5