Abstract
Structure and microsegregation was studied in directionally solidified Ni-based superalloy of the chemical composition Ni-11.7W-8.46Co-5.04Cr-4.72Al-1.05Nb-1.05Ti-0.96Mo-0.16C (wt. %). The microstructure of Ni-based superalloy consisted of γ-matrix with coherent γ'-precipitates and complex monocarbides of (Nb,Ti,W)C type. It was shown that during solidification W and Co segregated in the dendrite cores with partition ratios higher than 1, and Ni, Cr and Al segregated in the interdendritic region with partition ratios lower than 1. At a constant temperature gradient at the solid-liquid interface of 12 000 K.m^-1, the measured partition ratios for Ni, W, Co, Cr, and Al depended neither on growth rate chosen from the interval <2.78 x 10^-6; 4.17 × 10^-5> m.s^-1 nor on morphology of the solid-liquid interface.

Key words
Ni-based superalloy, directional solidification, microsegregation, partition ratio

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