Microstructure and Tensile Properties of Hot Isostatically Pressed Nickel-base Superalloy CM247LC

Abstract

CM247LC alloy has been processed through two different routes, viz. investment casting and powder metallurgical route. The powder metallurgical route involves production of powder through inert gas atomization followed by consolidation using hot isostatic pressing (HIP). A comparative study has been carried out on microstructure and mechanical properties of the material processed through both routes to assess the efficacy of the powder metallurgical process as a viable alternative to the investment casting route. The HIPed material is free from deleterious prior particle boundaries and coarse primary γ′ and has finer grain size compared to cast material. The HIPed material exhibits higher strength and ductility at room temperature, whereas ductility of HIPed alloy at 760°C is less than for the cast alloy. Detailed microstructural analysis and thermodynamic calculation reveal that network of carbides at the grain boundary of HIPed material causes lower ductility although HIPed material exhibits better strength than cast material, even at higher temperature. This study establishes the potential of HIP process to manufacture near net shape components of complex configuration through powder metallurgy route.