Microstructures and mechanical properties of a NI-CR-AL alloy by EB-PVD

Ni-Cr-Al-Y superalloy foil with 0.2 mm thickness was deposited by EB-PVD process, and its microstructure and mechanical properties were studied by AFM, SEM and TEM. Column crystals were observed in the as-deposited samples, which contributes to growing pattern of grains during the production of superalloy. Column crystals transformed into equiaxed crystals after being annealed at 760°C for 16 hours under vacuum condition, γ′ phase was observed. Factograghs of tensile specimens show that brittle rupture occurred along the intergranular of column crystals of as-deposited specimens, which attributes to the loose structures with weak cohesion between column crystals. But the fractures of annealed specimens were tough fractures. Test results show that mechanical properties of annealed specimens were improved sharply, compared with those of as-deposited specimens. The tensile strength of annealed specimens is 587.6 MPa, and the elongation reaches to 11.3%.