Creep deformation and rafting in nickel-based superalloys simulated by the phase-field method using classical flow and creep theories

A phase-field model has been developed to simulate the evolution of both (γ + γ′) microstructure and inelastic strain between γ′ phases (i.e. γ channel) during high-temperature creep in nickel-based superalloys. Inelastic strain is defined as the sum of time-independent and time-dependent components. Previously reported mechanical properties of single-phase γ alloys are considered in the calculation of inelastic strain evolution. A two-dimensional phase-field simulation is performed, and the results of microstructure evolution and the creep rate vs. time curve are fitted to the experimental data of the high-temperature creep of CMSX-4. The slope of the creep rate vs. time curve during the initial stage of transient creep, the plasticity preference in different types of γ channels, and the rafting phenomenon are reproduced well by the simulation. Furthermore, it is demonstrated that the creep rate increases locally at γ/γ′ interfaces when the rafted structure is formed.