Topologically Close-Packed μ Phase Precipitation in Creep-Exposed Inconel 617 Alloy
- 735 Downloads
Two creep-exposed Inconel 617 alloy samples [923 K (650 °C) for 45,000 hours and 973 K (700 °C) for 4000 hours] have been studied using analytical electron microscopy and X-ray diffraction techniques. The thermodynamically predicted equilibrium phases in Inconel 617 alloy were compared with the phases observed which are molybdenum-enriched, topologically close-packed μ-phase, along with precipitates of gamma-prime (γ′), M23C6 and Ti(C,N). The μ-phase precipitates were in the size range 60 to 500 nm (with some larger agglomerates); they were situated both within the grains, along twin and grain boundaries, and near intra- and intergranular carbides. The stacking faults in the μ-phase were observed in high magnification electron microscopy. The precipitation of the μ-phase in these samples is significant for the potential use of this alloy in future generation steam power plants as the appearance of the μ-phase is associated with an increased tendency for cracks and voids to initiate. The μ-phase has not been previously identified in the literature relating to creep or thermal exposure of Inconel 617 alloy.
KeywordsThermal Exposure Solid Solution Strengthen Creep Exposure Equilibrium Volume Fraction Thermodynamic Equilibrium Phase
The authors would like to thank ALSTOM Power Ltd. for supplying creep-exposed Inconel 617 alloys and wish to thank the UK Government’s Technology Strategy Board for providing financial support to carry out this work. Mr G. Clark is thanked for help with microscopy and Mr T Forryan is thanked for preparing samples for XRD analysis.
- 1.J.C. Hosier and D.J. Tillack: Met. Eng. Q., 1972, vol. 12 (3), pp. 51–55.Google Scholar
- 2.W.L. Mankins, J.C. Hosier, and T.H. Bassford: Metall. Mater. Trans. B, 1974, vol. 5, pp. 2579–90.Google Scholar
- 5.C.T. Sims: in Superalloys II, C.T. Sims, N.S. Stoloff, and W.C. Hagel, eds., John Wiley, New York, 1987, pp. 217–40.Google Scholar
- 10.N.D. Evans, P.J. Maziasz, J.P. Shingledecker, and Y. Yamamoto: Mater. Sci. Eng. A, 2008, vol. 498 (1–2), pp. 412–20.Google Scholar
- 15.M. Raghavan, R.R. Mueller, G.A. Vaughn, and S. Floreen: Metall. Trans. A, 1984, vol. 15A, pp. 783–92.Google Scholar
- 16.H. Kirchhöfer, F. Schubert, and H. Nickel: Nucl. Technol., 1984, vol. 66 (1), pp. 139–48.Google Scholar
- 19.N. Saunders, Z. Guo, X. Li, A.P. Miodownik, and J.-P. Schillé: in Superalloys 2004, K.A. Green, T.M. Pollock, and H. Harada, eds., TMS (The Minerals, Metals & Materials Society), Warrendale, PA, 2004, pp. 849–58.Google Scholar
- 20.Y. Hosoi and S. Abe: Metall. Trans. A, 1975, vol. 6A, pp. 1171–78.Google Scholar
- 21.O.F. Kimball, G.Y. Lai, and G.H. Reynolds: Metall. Trans. A, 1976, vol. 7A, pp. 1951–52.Google Scholar
- 22.T. Takahashi, J. Fujiwara, T. Matsushima, M. Kiyokawa, I. Morimoto, and T. Watanabe: Trans. ISIJ, 1978, vol. 18, pp. 221–24.Google Scholar
- 23.S. Kihara, J.B. Newkirk, A. Ohtomo, and Y. Saiga: Metall. Trans. A, 1980, vol. 11A, pp. 1019–31.Google Scholar
- 25.K. Schneider, W. Hartnagel, P. Schepp, and B. Ilschner: Nucl. Technol., 1984, vol. 66 (2), pp. 289–95.Google Scholar
- 26.G.N. Maniar and A. Szirmae, eds.: Manual on Electron Metallography Techniques, ASTM Special Technical Publication 547, American Society for Testing and Materials, Philadelphia, PA, 1973, pp. 3–24.Google Scholar
- 27.K.C. Thompson-Russell and J.W. Edington: Electron Microscope Specimen Preparation Techniques in Materials Science, vol. 5, Philips Technical Library, Monographs in Practical Electron Microscopy in Materials Science, Macmillan Publishers Ltd, London, 1977.Google Scholar
- 28.K.R. Vishwakarma, N.L. Richards, and M.C. Chaturvedi: Mater. Sci. Eng A, 2008, vol. 480 (1–2), pp. 517–28.Google Scholar
- 29.W. Betteridge and J. Heslop, eds.: The Nimonic Alloys and Other Nickel-Base High-Temperature Alloys, Edward Arnold (Publishers) Ltd., London, 1959, pp. 71–72.Google Scholar
- 30.R. Krishna, S.V. Hainsworth, S.P.A. Gill, A. Strang, and H.V. Atkinson: Proc. 2nd Int. ECCC Conf. on ‘Creep & Fracture in High Temperature Components—Design & Life Assessment’, I.A. Shibli and S.R. Holdsworth, eds., 21–23 April 2009, Zurich, pp. 764–76.Google Scholar
- 31.Thermo-Calc Software AB (Version 4), http://www.thermocalc.com, Stockholm, Sweden, August 2006.
- 32.P.J. Ennis, K.P. Mohr, and H. Schuster: Nucl. Technol., 1984, vol. 66 (2), pp. 363–68.Google Scholar