Microstructural specificity of optimal creep performance in Ni-based single crystal superalloys under 980°C-250 MPa and 1100°C-137 MPa conditions

Ni-based single crystal superalloys for turbine blades experience multimodal creep. Current microstructural design lacks tailored γ-γ′ microstructures for specific conditions. Five initial microstructures with similar morphology and varying γ′ size were creep tested under 980°C/250 MPa and 1100°C/137 MPa. Both conditions showed single-peak creep life evolution, but the creep life peak shifted toward smaller γ′ sizes under the higher temperature. This shift arises from coupled effects of γ′ size on dislocation motion, lattice misfit on interfacial dislocation density and extra damage from TCP phase, offering insights for optimizing microstructures under complex service conditions.