Creep properties of different γ′-strengthened Co-base superalloys

► Creep strength of some Co-base alloys similar to Ni alloy IN100 at 850 °C. ► Strengthening of grain boundaries is crucial for the creep strength. ► Morphology of grain boundaries has a strong impact on creep properties. ► Activation energy for creep similar to Ni-base superalloys. ► Plasticity by dislocation activity in matrix channels and shearing of γ′-particles.