A phase field model for isothermal crystallization of oxide melts

We present a multicomponent multi-phase field model for isothermal crystallization of oxide melts. The bulk thermodynamic properties of the liquid as a function of composition are retrieved from the FACT thermodynamic database for oxide systems. For solid phases modeled as stoichiometric in the thermodynamic database, a paraboloid Gibbs energy is introduced with specific constraints to ensure correct phase equilibria and minimal solubility in the stoichiometric phase. The interfacial mobility can show strong anisotropy and the interfacial energy can have weak anisotropy, since both faceted and dendritic growth morphologies are important for crystallization in oxide systems. The possibilities of the model are illustrated with three case studies considering crystallizing and dissolving solid phases in a CaO–Al2O3–SiO2 melt. These case studies show the influence of the diffusion mobilities on the diffusion path, the tie-line selection in a ternary system and the effect of the surface energy on dendritic growth.