| Abstract Scope |
Ni-based superalloys are characterized high strength and corrosion resistance at temperatures. This makes them a key group of materials used in the aviation industry. This work aimed to determine the influence of temperature on the precipitate's stability in the cast MAR-M247 produced via directional solidification. The microstructure, chemical composition, phase constitution, phase transformation temperatures, and microhardness of the castings produced with various withdrawal rates and shell mold temperatures were investigated by X-ray diffraction, scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, thermodynamic simulation, and differential scanning calorimetry. Solution heat treatment led to the dissolution of the γ' precipitates and the complete dissolution of the (Cr, W, Mo)5B3 borides and the Ni7(Hf, Zr)2 phases. Secondary γ' precipitates in dendritic regions possess cube-like morphology and finer size than the as-cast state. In the interdendritic spaces, the secondary γ' precipitates have a much more complex morphology originating from the coagulation of finer precipitates. |