Coupling phase field with creep damage to study γʹ evolution and creep deformation of single crystal superalloys

A phase-field model coupling with elastoplastic deformation and creep damage has been built to study the microstructural evolution and deformation behavior for Ni‒Al single crystal alloy during the whole creep processing. The relevant experiments were conducted to verify the model validity. The simulation results show that under the tensile creep at 1223 K/100 MPa, cubic γʹ phases coarsen along the direction parallel to the axis of tensile stress during the first two creep stages; and spindle-shaped and wavy γʹ phases are formed during tertiary creep, similar to the experimental results. The evolution mechanism of γʹ phases is analyzed from the perspective of changes of stress and strain fields. The “island-like” γ phase is observed and its formation mechanism is discussed. With the increase of creep stress, the directional coarsening of γʹ phase is accelerated, the steady-state creep rate is increased and the creep life is decreased. The comparison between simulated and experimental creep curves shows that this phase-field model can effectively simulate the performance changes during the first two creep stages and predict the influence of creep stresses on creep properties. Our work provides a potential approach to synchronously simulate the creep microstructure and property of superalloys strengthened by γʹ precipitates.