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Atom Probe Field Ion Microscopy of Model Ni-Al-Be Superalloys

Published online by Cambridge University Press:  02 July 2020

R. C. Thomson ,
K. F. Russell  and
M. K. Miller
R. C. Thomson
Affiliation:
Institute for Polymer Technology and Materials Engineering, Loughboroug University, Loughborough, Leicestershire, LEI 1 3TU, UK.
K. F. Russell
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6376, USA.
M. K. Miller
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6376, USA.
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Extract

Nickel-based superalloys used in jet engines consist of a face-centred cubic Ni matrix, γ, containing a high density of Ll2-ordered Ni3Al precipitates, γ´. At high temperatures the strength of the alloy depends primarily on the strength of the γ´ phase, which begins to decrease above approximately 750°C, limiting the maximum operating temperature of the superalloy. The possibility of strengthening the γ´ phase by solid-state precipitation within the γ´ phase has been investigated in model Ni-Al superalloys containing Be. Beryllium, a light element, is also expected to be a potent solid solution strengthener in the γ´ matrix.

Four alloys were manufactured with compositions Ni-18.8 at. % Al-1.6% Be, Ni-19.0 at. % Al-2.6% Be, Ni-17.9 at. % Al-5.4% Be and Ni-15.9 at. % Al-11.9% Be. These Al levels result in a volume fraction of γ´ phase similar to that present in a commercial superalloy, and the Be addition places the superalloys in the γ-γ´-NiBe region of the ternary phase diagram, Fig. 1.

Type
Phase Transformations in Metals and Alloys
Information
Microscopy and Microanalysis , Volume 3 , Issue S2: Proceedings: Microscopy & Microanalysis '97, Microscopy Society of America 55th Annual Meeting, Microbeam Analysis Society 31st Annual Meeting, Histochemical Society 48th Annual Meeting, Cleveland, Ohio, August 10-14, 1997 , August 1997 , pp. 695 - 696
Copyright
Copyright © Microscopy Society of America 1997

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References

1. Thomson, R.C., Russell, K.F. and Miller, M.K., J. de Phys. IV, 6-C5 (1996) 259.Google Scholar

2. Miller, M.K. and Thomson, R.C., J. de Phys. IV, 6-C5 (1996) 277.Google Scholar

3. This research was sponsored by the Division of Materials Sciences, U. S. Department of Energy, under contract DE-AC05-96OR22464 with Lockheed Martin Energy Research Corp. and the Royal Society, U.K. This research was conducted utilizing the Shared Research Equipment (SHaRE) User Program facilities at Oak Ridge National Laboratory.Google Scholar