This paper presents the results of analysis of superalloys microstructures with different structures: polycrystalline nickel-based superalloy René 80, Mar-M 200Hf directionally solidified with columnar grains and single crystal CMSX-4. Microstructure studies were performed using a scanning electron microscope Hitachi FE-SEM SU-70 and S-3400N equipped with a Thermo Scientific Noran System for analysis of chemical composition by X-ray dispersion. Metallographic microsections of the rods before and after heat treatment was performed, which were electrolytically etched using different reagents. The morphology of γ phase precipitates in the interdendritic areas and dendritic cores was analyzed. Single crystal rods of nickel superalloy CMSX-4 were cast by Bridgman technique in a vacuum furnace of ALD Vacuum Technologies. Rods were withdrawn with rate: 1mm/min and 5mm/min. EDS X-ray microanalysis showed significant differences in chemical composition between the cores dendrites and eutectic regions. Significant differences in the number of dendrites, the shape and length of the arms were observed. A lower speed rate causes that amount of eutectic is lower but value of primary dendrite arm spacing is higher, while a higher withdraw rate increases the amount of eutectic and decreases primary dendrite arm spacing.
Detailed Analysis of the Solution Heat Treatment of a Third-Generation Single-Crystal Nickel-Based Superalloy CMSX-10K®
