Dislocation-mediated rejuvenation of deformation energy in a novel nickel-based single crystal superalloy

Abstract

Recrystallization in Ni-based single crystal superalloys (NiSXs) frequently occurs during manufacturing or transportation, posing challenges to ensuring the integrity and performance of turbine components. In this study, we propose an efficient rejuvenation protocol for a fourth-generation Ni-based single crystal superalloy following deformation. By gradually increasing the temperature to just below the sub-solidus temperature and applying annealing, we effectively suppress the occurrence of recrystallization. Experimental evidence demonstrates that partial dissolution of γ' precipitates broadens the γ channels, promoting interface migration and facilitating dislocation annihilation. This approach reduces the driving force for recrystallization and helps preserve the single-crystal structure of the superalloy after solution treatment. Molecular dynamics (MD) simulations are employed to analyze the deformation and recovery mechanisms; results show that increased deformation leads to a significant rise in dislocation density. The simulations further reveal that superalloys with wider γ channels exhibit enhanced coordinated deformation capability, attributed to the reduced obstruction to dislocation motion imparted by these wider channels. This study elucidates the effectiveness of the proposed rejuvenation protocol and offers valuable insights for the maintenance and longevity of single-crystal turbine blades.