Effect of the Directional Solidification Conditions and the GTE Blade Size on the Dendritic Structure of Nickel Superalloys

Abstract—The influence of the size and structural elements of GTE and GTU blade model samples on the dendritic structure of a high-temperature ZhS-32 alloy is studied. The sizes of dendrites, γ' phase, and γ/γ' eutectic; the porosity; and the dendritic segregation in castings are estimated using optical and electron microscopy and electron-probe microanalysis. The experimental results indicate that, without a liquid-metal cooler, a structure with the largest sizes of dendrites, γ' phase particles, and γ/γ' eutectic forms in the thick sections of the GTU blade samples. The maximum porosity and dendritic segregation in them are detected. When the temperature gradient in the GTE blade model samples increases (in the case of a liquid-metal cooler), a structure with significantly smaller dendrites and phase particles, lower porosity, and weaker dendritic segregation is found to form in them. The size, design, and method of solidification of the blades is shown to affect the conditions of subsequent heat treatment and gasostatic pressing.