Structural peculiarities of γ/γ'-MeC directionally crystallized eutectics

Microstructure of directionally crystallized casting of nickel eutectic γ/γ'-Nb alloy is investigated. Directed structure formation during crystallization starts in the zone of competitive growth after isolation of primary niobium carbides appearing to be basic ones for eutectics crystallization from which eutectic colony grains develop. Texture in axial and azimuthal directions of columnar colony grains is investigated. Evaluation of effect of alloy chemical composition, crystallization rate and thermophysical properties of crucible material on the formation of surface MeC carbides during crystallization of casting with plain growth front is given