Abstract
The character of dendrite segregation in Ni3Al-based intermetallic VKNA-type alloy single crystals with a dendritic–cellular structure is studied. Distribution coefficient k d of an alloying element (AE) in the alloy during solidification k d = c d.a.I/c 0 (c 0 is the AE content in the alloy (liquid phase composition), c d.a.I is the AE content in primary dendrite arms of the alloy (in the solid phase)) and segregation coefficient k s = c d.a.I/c i.d (c i.d is the AE content in the interdendritic space) have been found. A comparative study of the dendrite segregation parameters in VKNA-nype Ni3Al-based intermetallic alloys and the well-known ZhS36-type nickel superalloy shows that the intermetallic alloys satisfy to the rule deduced for two- and three-component nickel-based superalloys: if an introduced AE increases the melting temperature of the basic metal, we have k d > 1 (Co, W, Re); if it decreases the melting temperature, we have k d < 1 (Al, Ti, Cr, Mo). Dendrite segregation coefficients k s are dependent on the proportion of the AE contents in the alloys. In nickel superalloys, the dendrite segregation of aluminum, tungsten, and rhenium is higher than that in the intermetallic alloys. The dendrite segregation coefficients of tungsten and rhenium is higher by a factor of 1.5–2 than that in the VKNA-type intermetallic alloys with a low content of refractory metals. This can be due to the retardation of diffusion of refractory metals in the solid phase of a nickel superalloy highly alloyed with these elements.
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Original Russian Text © A.A. Drozdov, K.B. Povarova, A.E. Morozov, A.V. Antonova, M.A. Bulakhtina, N.A. Alad’ev, 2015, published in Metally, 2015, No. 4, pp. 48–55.
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Drozdov, A.A., Povarova, K.B., Morozov, A.E. et al. Dendrite segregation in Ni3Al-based intermetallic single crystals alloyed with Cr, Mo, W, Ti, Co, and Re. Russ. Metall. 2015, 551–557 (2015). https://doi.org/10.1134/S0036029515070058
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DOI: https://doi.org/10.1134/S0036029515070058