Effects of microstructure on the creep properties of a new Ni-Co base superalloy

The effects of microstructure on the creep behavior in a new developed Ni-Co base superalloy were investigated and two microstructures were obtained by different heat treatments. The results show that the air cooling microstructure, consisting of large spherical γ′ and small spherical γ′, resulted in a slow creep rate and small creep strain. While the slow cooling microstructure, consisting of large flowery γ′ and small spherical γ′, resulted in a fast creep rate and large creep strain. The γ channel and γ′ morphology are two main factors for these differences, the large γ channel and flowery γ′ in the slow cooling microstructure causing the dislocations slip easily in the γ matrix and cut into the γ′ precipitates with low stress.