Tips and Tricks: Selecting the Right Model for Your Scheil Solidification Calculation
Plots showing results from Scheil calculations using the available model configurations in Thermo-Calc: Classic Scheil, Scheil with Back Diffusion in Primary Phase, Scheil with Fast Diffusers, and Scheil with Solute Trapping.
Comparison of Equilibrium, Classic Scheil, and Scheil with Back Diffusion in Primary Phase solidification simulation results for Ni-30Cr-5Nb (wt.%). As the plot shows, back diffusion has a negligible effect on the predicted solidification behavior at a cooling rate of 10 °K/s.
Comparison of Equilibrium, Classic Scheil, and Scheil with Back Diffusion in primary phase solidification simulation results for Al-5Mg (wt.%). In this case, back diffusion of Mg has a pronounced effect of shifting solidification behavior towards global equilibrium and decreases the likelihood of forming a eutectic at the end of solidification. Back diffusion becomes more significant as the cooling rate is decreased.
A Scheil solidification simulation results for a Fe-0.18C-0.5Mn (wt.%) steel, showing the effect of treating carbon as a fast diffuser. Diffusion of carbon in the solid during solidification drastically reduces segregation and consequently increases the terminal solidus temperature.
Comparison of Equilibrium, Classic Scheil, and Scheil with Solute Trapping solidification simulation results for Al-5Cu (wt.%). Increasing the solidification speed results in a loss of local equilibrium at the solid/liquid interface and a shift toward partitionless solidification.