Numerical computations for temperature, fraction of solid phase and composition couplings in ternary alloy solidification with three different thermodynamic data-acquisition methods

In this paper, a previously proposed numerical model for binary alloy solidification, and the corresponding algorithm for solving the strong coupling among the solidification temperature, solid fraction, and liquid composition (T–fS–CLT–fS–CL), are extended to ternary alloys. The feasibility of the extended numerical method is demonstrated by sample simulations for the directional solidification of blade-like castings of Al–Cu–Si alloys using three different thermodynamic data-acquisition methods: direct coupling with the CALPHAD software Thermo-Calc via the TQ6-Interface, using the “mapping technique” and regression functions. The computational efficiency and the accuracy of the calculation results of the three different methods are compared. The present numerical simulations confirm that thermodynamic data-acquisition method of using regression functions and the “mapping technique” are much more efficient than that of direct coupling with Thermo-Calc.

► Model and algorithm for ternary alloy solidification are proposed.
► Solidification of Al10.5Cu7.5Si alloy is simulated using three methods.
► The simulation method of using regression functions is the most efficient.
► Using regression functions spends 65% of CPU-time cost by the “mapping technique”.