Numerical modelling of precipitation of topologically close-packed phases in nickel-base superalloys

A new mesoscale model was developed to understand the precipitation sequence of topologically close-packed (TCP) phases in single-crystal nickel-base superalloys. Nucleation and growth phenomena are described in detail. The model allows the multicomponent, multiphase and multiparticle calculation of TCP phase volume fractions and size distributions from supersaturated solid solution to thermodynamic equilibrium. It is based on the numerical Kampmann–Wagner method and applies CALPHAD (ThermoCalc) and DICTRA methodology for thermodynamics and diffusion. The capabilities of the simulations are demonstrated by the prediction of the size distributions of TCP phases and comparison with experimental data.