We develop a phase-field model for the simulation of diffusion-limited precipitation in Ni-based superalloys with industry-relevant chemical complexity. The thermodynamic formulation is validated by comparisons to respective ThermoCalc equilibrium calculations and DICTRA sharp interface simulations. Furthermore, an elastic term is included in the model to account for the misfit stresses as well as elastic inhomogeneities between the two considered phases.
First, we consider the coarsening kinetics of $\gamma'$-precipitates in single crystalline Ni-based cast-alloys. 2D simulations show that the additional influence from the missfit strain leads to a systematically faster coarsening-evolution as compared to respective simulations without elastic effects and predictions from the classical LSW-theory (Ostdald-ripening).
As a second example, we consider the coarsening kinetics of meta-stable gamma''-precipitates in the well-known Ni-based wrought-alloy Inconel 718, which involves a cubic to tetragonal transformation.
Here, we study the evolution of microstructural characteristics, such as the mean particle diameter as well as the overall phase fraction as function of the basic two heat treatment parameters: temperature and time.