Superior creep resistance in a γ′-strengthened Co-based single-crystal superalloy at 760°C and ∼90% yield strength

Abstract

The creep mechanism of a Co-based single-crystal (SX) superalloy at 760°C/800 MPa (∼90% yield strength) was revealed and differed from those of Re-containing Ni-based SX superalloys. Experimental alloy displays superior creep resistance in the early creep stage, likely due to the accumulation of matrix dislocations and W segregation-assisted shearing of γ′ phase by leading Shockley partial dislocations instead of Co and Cr segregation a < 112> SF ribbons in Re-containing Ni-based SX superalloys during the accelerating creep stage. Segregation-assisted local χ/η phase transformations at SFs stabilize and enhance SF interactions, contributing to the subsequent slow accelerating creep stage.