The Homogenisation of Single-Crystal Superalloys
G. S. Hillier and H. K. D. H. Bhadeshia
Abstract
The homogenisation of nickel-base superalloys is best carried out at a temperature within the gamma phase field, provided that the alloy does not undergo incipient melting before the gamma' solvus is reached. The temperature range between the gamma' solvus and the solidus of the inhomogeneous alloy is called the "heat-treatment window". This work is an investigation of the factors determining the heat-treatment window, as a function of alloy composition for a range of single crystal superalloys. The homogenisation behaviour is followed using various microanalysis techniques.
It is found that the heat-treatment window variations can be qualitatively understood in terms of the effect of Ti on the solidus temperature of superalloys and in terms of its ability to increase the amount of gamma/gamma' eutectic obtained in as-cast single crystal superalloys. Some clear trends in the segregation behaviour of various alloying elements are also established and discussed.
This research paper examines the thermal processing of nickel-base single crystal superalloys, focusing specifically on how different chemical elements influence the homogenization process. The authors investigate the heat-treatment window, which is the critical temperature range between the point where the strengthening phase dissolves and the point where the metal begins to melt. Through detailed microanalysis, the study demonstrates that adding titanium narrows this available temperature range by lowering the alloy's melting point and increasing the volume of certain eutectic structures. The findings suggest that while titanium complicates heat treatment, achieving a uniform microstructure is still possible through extended heating durations. Ultimately, the work provides a scientific framework for understanding how segregated elements behave during the production of high-performance turbine materials.
Proceedings of the Sheffield Centenary Conference on Perspectives
in Metallurgical Development,
The Metals Society, London, 1984, pp. 183-187.
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- "The Homogenisation of Single-Crystal Superalloys"
Proceedings of the Sheffield Centenary Conference on Perspectives
in Metallurgical Development,
The Metals Society, London, 1984, pp. 183-187
G.S. Hillier and H.K.D.H. Bhadeshia
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ISIJ International, Vol. 38, 1998, 495-502.
S. Yoshitake, V. Narayan, H. Harada, H. K. D. H. deshia and D. J. C. MacKay
- "Prediction of Creep Rupture Life in Nickel-Base Superalloys Using Bayesian Neural Networks"
Journal of The Japan Insitute of Metals, Vol. 63, 1999, 905-911
H. Fujii, D. J. C. MacKay, H. K. D. H. Bhadeshia, H. Harada and K. Nogi
- "Design of New Creep-Resistant Nickel-Base Superalloys for Power Plant Applications"
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F. Tancret, H. K. D. H. Bhadeshia, D. J. C. MacKay, T. Sourmail, M. Yescas, R. W. Evans, C. McAleese, L. Singh and T. Smeeton
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Proceedings of the 6th International Charles Parsons Turbine Conference, Engineering Issues in Turbine Machinery, Power Plant and Renewables, eds A. Strang, R. D. Conroy, W. M. Banks, M. Blackler, J. Leggett, G. M. McColvin, S. Simplson, M. Smith, F. Starr and R. W. Vanstone, Institute of Materials, London, 2003, 525-535.
F. C. Tancret and H. K. D. H. Bhadeshia
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