Coupled Analysis of Microstructure Evolution with Creep Deformation in Nickel-Based Superalloys by the Phase-Field Method

Directional coarsening of the ’ phase (rafting) during creep in nickel-based superalloys was simulated by a phase-field model that calculates the evolution of both the ( + ’) microstructure and the inelastic strain in the  phase. A two-dimensional simulation revealed that directional coarsening affected the macroscopic creep behavior and that the strain rate increased temporarily. The creep rate–time curve of the initial stage of transient creep was successfully reproduced by the simulation. Furthermore, the results of a three-dimensional simulation showed that the dislocations prefered the  phase perpendicular to the external tensile stress and demonstrated that the strain rate increased locally at the /’ interface with a curvature when rafting occurs.