Field-Assisted Sintering of Nickel-Based Superalloy Powder for High-Temperature Hybrid Turbine Disc Applications

Turbine discs are currently made of nickel-based superalloys, known for their high strength and creep resistance at high temperatures. Hybrid or dual-microstructure turbine discs allow for significant weight savings, but current methods of joining dissimilar nickel-based superalloys such as friction welding exhibit a heat-affected zone and localized melting at the interface, leading to weak bonding. Here, we show that field-assisted sintering technology may be used to sinter the nickel-based superalloy powder CM247LC to high relative density, and the effect of sintering temperature and time on porosity, grain size, and mechanical properties of CM247LC is investigated. We also show that the same technology may be used to form hybrid discs with a solid Inconel 718 core and a powder-sintered CM247LC rim without the formation of a heat-affected zone at the interface. Two different joining angles between the two materials in the hybrid discs are explored, and preliminary results suggest that the joining angle does not affect the tensile properties of the material interface.