Precipitation kinetics and creep properties of multicomponent Ni-based superalloys

Abstract

The evolution kinetics and creep characteristics of the γʹ phase are closely related to the mechanical properties of multicomponent Ni-based superalloys. Thus, an investigation of the continuous precipitation-to-creep behavior of the γʹ phase is needed. By using crystal viscoplastic multicomponent phase-field simulation, the effects of Co on the evolution kinetics of the γʹ-(Ni, Co)₃(Al, Ta) phase and creep rafting are revealed in Ni-12.2Al-xCo-2.5Ta (x = 6, 8, and 10 at.%) multicomponent superalloys. Co promotes the precipitation of the γʹ phase with increasing volume fraction and particle number, while the particle radius and coarsening rate of the γʹ phase are reduced. The high Co content results in a low creep strain and long creep life, and the degeneration of the γʹ phase becomes slow in the accelerated creep stage. A higher volume fraction of the γʹ phase is maintained, and the stability of the γʹ rafts is elevated after creep. Moreover, the contributions of the activated slip systems to the creep properties are analyzed, and the octahedral slip systems \(\left( {\overline{1}\overline{1}1} \right)\left[ {101} \right]\) under tensile stress and \(\left( {\overline{1}11} \right)\left[ {0\overline{1}1} \right]\) under compressive stress dominate the creep strain. The phase-field simulation provides continuous precipitation and creep morphology kinetics predictions for multicomponent Ni-based superalloys.

Graphical abstract