Cooling Rate Dependent Morphology of the γ' Precipitates in Nickel-Base Superalloy Udimet 500

Abstract:

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The morphology of the γ΄ precipitates during continues cooling of a nickel-base superalloy, Udimet 500, was studied using scanning electron microscopy and X-ray diffraction technique. The samples were full solutioned at 1200oC and then were cooled to ambient temperature under different cooling rates, 15, 1, 0.2, 0.05oC/min and air cooling. The unconstrained γ-γ΄ misfit values for each sample were calculated using the electrolytic extracted γ΄ precipitates. According to the results, by decreasing the cooling rate, not only the size, volume fraction and interparticle spaces of the  precipitates were increased, but also depending on the γ-γ΄ lattice misfits the corresponding  morphology was changed from spherical to cubic, then flower-like and finally dendritic shape. The observations are discussed in view of the compositional changes of γ/γ΄ phases and elastic strain considerations of their interfaces which will be described in detail in the article.

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Edited by:

M. Heilmaier

Pages:

108-113

DOI:

10.4028/www.scientific.net/AMR.278.108

Citation:

M. K. Savadkoohi et al., "Cooling Rate Dependent Morphology of the γ' Precipitates in Nickel-Base Superalloy Udimet 500", Advanced Materials Research, Vol. 278, pp. 108-113, 2011

Online since:

July 2011

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