Modeling morphological evolution and rafting of γ′ precipitates in Ni-Al superalloys under applied stresses

The morphological evolution and rafting of γ′ phase particles in Ni-Al superalloys under applied stresses were investigated. A computer model based on a diffuse-interface phase-field model was employed. In this model, a two-phase microstructure is described by a concentration field and a three-component long-range order parameter field. The temporal evolution of the field variables was determined by solving the non-linear Ginzburg-Landau and Cahn-Hilliard equations. The elastic inhomogeneity was taken into account. It is demonstrated that an applied stress may result in a raft-like microstructure and the rafting of γ′ phase is dependent on the magnitude, the applying direction, and the type of the applied stress.