Microstructural Investigations of Nickel-Based Superalloys with Different Structure

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Abstract:

This paper presents the results of analysis of superalloys microstructures with different structures: polycrystalline nickel-based superalloy René 80, Mar-M 200Hf directionally solidified with columnar grains and single crystal CMSX-4. Microstructure studies were performed using a scanning electron microscope Hitachi FE-SEM SU-70 and S-3400N equipped with a Thermo Scientific Noran System for analysis of chemical composition by X-ray dispersion. Metallographic microsections of the rods before and after heat treatment was performed, which were electrolytically etched using different reagents. The morphology of γ phase precipitates in the interdendritic areas and dendritic cores was analyzed. Single crystal rods of nickel superalloy CMSX-4 were cast by Bridgman technique in a vacuum furnace of ALD Vacuum Technologies. Rods were withdrawn with rate: 1mm/min and 5mm/min. EDS X-ray microanalysis showed significant differences in chemical composition between the cores dendrites and eutectic regions. Significant differences in the number of dendrites, the shape and length of the arms were observed. A lower speed rate causes that amount of eutectic is lower but value of primary dendrite arm spacing is higher, while a higher withdraw rate increases the amount of eutectic and decreases primary dendrite arm spacing.

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Periodical:

Key Engineering Materials (Volumes 592-593)

Pages:

557-560

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Online since:

November 2013

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[1] J. Sieniawski, Kryteria i sposoby oceny materialow na elementy lotniczych silnikow turbinowych, Oficyna Wydawnicza Politechniki Rzeszowskiej, Rzeszow, 1995. (in polish).

Google Scholar

[2] D. Szeliga, K. Kubiak, A. Burbelko, R. Cygan, W. Ziaja, Modelling of grain microstructure of IN-713C castings, Solid State Phenomena. 197 (2013) 83-88.

DOI: 10.4028/www.scientific.net/ssp.197.83

Google Scholar

[3] C. R. Reed, The Superalloys: Fundamentals and Applications. Cambridge University Press, Cambridge (2006).

Google Scholar

[4] D. Szeliga, K. Kubiak, G. Jarczyk, The influence of the radiation baffle on predicted temperature gradient in single crystal CMSX-4 castings, International Journal of Metalcasting. 3 (2013) 17-23.

DOI: 10.1007/bf03355555

Google Scholar

[5] A.J. Elliott, T.M. Pollock, Thermal analysis of the bridgman and liquid-metal-cooled directional solidification investment casting processes, Metallurgical and Materials Transactions A. 38 (2007) 871-882.

DOI: 10.1007/s11661-006-9085-2

Google Scholar

[6] W. Kurz, D.J. Fisher, Dendrite growth at the limit of stability: tip radius and spacing, Acta Metall. 29 (1981) 11-20.

DOI: 10.1016/0001-6160(81)90082-1

Google Scholar