AN INVESTIGATION OF MICROSEGREGATION AND LIQUID DENSITY REDISTRIBUTION DURING SOLIDIFICATION OF INCONEL 718

ISSN： 0098-6445

Source： Chemical Engineering Communications, Vol.196, Iss.6, 2009-06, pp. : 754-765

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Abstract

In order to investigate micro-segregation behavior and liquid density variation during solidification, microstructure and alloy element concentration in liquid of remelted samples quenched at different temperatures in the freezing range were investigated by SEM and EDAX, and the densities at different locations in liquid were calculated. Mass fractions of liquid and different solid phases were calculated using the Thermo-calc program for two alloy composition, Inconel 718 and segregated liquid. It was found that the segregation of Nb in liquid prompts the precipitation of high-Nb phases of  and Laves directly from the liquid, which results in the redistribution of Nb and density in the vicinity of these phases in the liquid. There is a region with low Nb content and density at the inter-precipitate that can change the mono-increasing distribution of liquid density in the mushy zone of Inconel 718; this phenomenon should be taken into account when considering liquid convection related to liquid density distribution.