Self-Propagating TCP Growth via Autonomously Generated Stacking Faults in Ni-Based Superalloys

We report a self-propagating growth mechanism for σ phase in Ni-based superalloys, mediated by autonomous stacking fault generation at phase tips. The misfit stress between the topologically close-packed phase (TCP phase) and the γʹ phase caused the formation of stacking faults along the elongation direction of the TCP particle, creating dual function that provide elemental diffusion highways and enhance TCP/γʹ structural compatibility. Pre-strained samples containing stacking faults (SFs) exhibited faster σ phase growth than defect-free controls, attributed to anisotropic propagation along SF planes. Our work revealed a novel defect-assisted growth paradigm for TCP phases in single crystal superalloys, offering critical insights for microstructural stability regulation. • Self-propagating TCP growth via stacking faults at phase tips. • Stacking faults enhance TCP/γ′ structural compatibility and diffusion. • Pre-strained samples with stacking faults promoted TCP growth than defect-free ones.