Work

Stacking fault strengthening via Mo-Ru synergism in Mo-rich Ni-based single crystal superalloys for superior ultra-high-temperature creep properties

Year: 2025

Type: article

Abstract: Stacking faults are critical planar defects in high-temperature alloys, exhibiting pronounced strengthening effects via self-interactions through the Lomer–Cottrell lock mechanism and interactions with other dislocation structures. However, under ultra-high temperature and low-stress conditions, the activation of stacking faults becomes difficult, thereby limiting their contribution to high-temperature creep resistance. In this study, it is demonstrated that through optimized alloy composition—particularly by substantially increasing the molybdenum (Mo) content to promote the formation of stacking faults and introducing ruthenium (Ru) to enhance their thermal stability—the strengthening effect associated with stacking fault interactions can be effectively realized at 1200 °C. At this temperature, a high volume fraction of the γ′ phase, the formation of dense dislocation networks induced by a designed negative lattice misfit, and the synergistic strengthening effect of the Kear–Wilsdorf (K–W) lock structure within the γ′ phase collectively suppress dislocation shearing from the γ matrix into the γ′ phase as well as their glide within the γ′ phase. This integrated mechanism effectively reduces the creep rate at 1200 °C.

Source: Journal of Materials Research and Technology

DOI: 10.1016/j.jmrt.2025.09.273