Characterization of as-cast single-crystal CMSX-4 superalloy turbine blades (Conference Paper)

摘要

Nickel-based single-crystal superalloys are widely used for production of high pressure turbine blades. The studied blades were obtained in an ALD Vacuum Technologies furnace by the Bridgman technique. Crystallization process was carried out with drawing rates of 1 mm/min, 3 mm/min and 5 mm/min. The dendrite microstructure based on the γ and γ' phases was characterized using X-Ray topography, Laue diffraction and transmission electron microscopy. The defect structure of the samples was examined with the positron annihilation lifetime spectroscopy. It was found that crystal orientation, lattice parameter of γ' phase and concentration of defects are correlated. The defect concentration increases in some areas which was the result of deviation of the primary dendrite arm from the <001> direction of crystallization. Only one type of point defects was detected.