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 (gamma + gamma ') microstructure and inelastic strain between gamma ' phases (i.e. gamma 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 gamma 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 gamma channels, and the rafting phenomenon are reproduced well by the simulation. Furthermore, it is demonstrated that the creep rate increases locally at gamma/gamma ' interfaces when the rafted structure is formed. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.