A new phase-field method for simulating γ′ precipitation in multicomponent nickel-base superalloys

The phase-field method is used to develop a new technique to simulate γ′ precipitation in multicomponent Ni-base superalloys. This technique generates the Gibbs free energy for both the γ and γ′ phases from the single function formalism of both phases in the CALPHAD method without using conventional CALPHAD software. The Gibbs free energy surfaces for eight-element multicomponent systems are used to confirm that there is an accurate coupling with the CALPHAD method, because they compare favorably with calculated results from Thermo-Calc. In addition, γ′ precipitation in a third-generation Ni-base superalloy containing eight components is simulated in one dimension with anti-phase effects of the γ′ phase on the precipitate interactions. The simulation results reveal late-stage enrichments of Re and W in the γ phase during coalescence of the γ′ precipitates.