DEVELOPMENT OF Ni-Co BASE ALLOYS FOR HIGH-TEMPERATURE DISK APPLICATIONS

The development of novel industrial cast and wrought (C&W) disk alloys with required combination of strength, creep and fatigue resistances is always desired and a challenge to material researchers. Recently, in the High Temperature Materials 21 Project (HTM21) led by the Japanese National Institute for Materials Science (NIMS), we proposed an innovative concept to design disk alloys. This concept is based on combining the characters of two kinds of γ−γ′ two-phase alloys (Ni-base and Cobase alloys) and leads up to some promising candidate alloys that can be processed by normal C&W processing route and shows at least a 30°C increase in temperature capability over the current C&W U720Li disk alloy. This paper shows the design idea, workability and mechanical properties of some Ni-Co-base alloys. Furthermore, full-scale-disk forgings were processed successfully for the evaluations of the processing ability and microstructure of new Ni-Co-base disk alloys, which demonstrated the advantages and possibility of Ni-Co-base disk alloys at the component level.