| Abstract Scope |
In some wrought Ni-based superalloys, grain-boundary precipitates strongly influence creep properties. Recently, we developed a novel Ni-Co-based superalloy with high W content which exhibits precipitation of several grain-boundary phases: γ', Cr-carbide, W-carbide and μ. In this study, the role of the grain-boundary phases on the creep properties is investigated. Two microstructures with different dominant grain-boundary phases are produced by multi-step aging treatments, without changing the amount and the size of γ' precipitates within grain interior. Metallographic analysis shows that dense precipitation of grain-boundary Cr-carbide, together with grain-boundary γ', reduces the minimum creep rate under compressive creep conditions, but at the expense of ductility and rupture life under tensile creep conditions, as compared to precipitation of grain-boundary W-carbide and μ. |