Phase-field simulation of precipitation kinetics and creep properties of Ni-Al-Cr/Ta superalloys.

The precipitation kinetics of γ′-Ni₃(Al, Ta) phase and creep properties of Ni-15Al-xTa at.% superalloys are investigated by the crystal plasticity phase-field simulation. The results show that the high Ta content brings a lower creep strain for the deceleration and steady creep stage, while the creep lifetime is shorter. The large external strain intensifies the creep damage and shortens the creep life of Ni-15Al-3Ta at.% superalloy. The kinetics evolution and elements distribution are revealed in the quaternary Ni-10Al-8.5Cr-xTa (x = 1.5 at.%, 2.0 at.%, 2.5 at.%) superalloys by the multi-component phase-field simulation. The anti-phase boundary (APB) changes the coarsening mechanism of γ′ phase, and Ta promotes the precipitation of γ′ phase with an increasing volume fraction and particle number. The composition difference between γ′ and γ phases increases with the rising of Ta content, the strong partitioning of Ta to γ′ phase strengthens the partitioning of Ni and Cr to γ matrix, and Ta shows a superiority than Al in the lattice site occupation of L1₂-Ni₃(Al, X) phases. As an important γ′ phase forming element, the optimization of Ta content is essential for improving the mechanical properties of Ni-based superalloys. [ABSTRACT FROM AUTHOR]