Latent heat method for macro-micro modeling of eutectic solidification

Two different numerical methods were used to simulate the solidification of eutectic alloys. The first one was the classical approach based on an implicit one-dimensional axisymmetric finite difference method (EUCAST program), while the second one involved a two dimension control volume implicit scheme with a boundary condition describing the heat flux at the casting-mold interface (BAMACAST program). To account for the heat evolution term in the conductivity equation, an original latent heat approach was introduced consisting of the calculation of the latent heat evolved by the fraction of solid formed as a function of time. In turn, the fraction of solid has been calculated based on nucleation and growth kinetics. The heat transfer coefficient used for simulation was determined based on an analytical approach for hollow cylinders. Gray cast iron and aluminum-silicon alloys of eutectic composition were used for the validation experiments. Experimental and computed data are compared, with excellent results for solidification time, undercooling, width of the mushy zone and heat transfer coefficient.