Phase-field simulation and analytical modelling of CaSiO3 growth in CaO-Al2O3-SiO2 melts

Abstract

Isothermal crystallization of a hexagonal crystal (Wollastonite) in ternary melts (CaO-Al2O3-SiO2) was simulated by quantitative phase-field simulation and analytical modelling. The dependence of initial composition, undercooling, interfacial energy and anisotropy strength on the growth behavior of Wollastonite was comprehensively investigated. According to simulation results, a transition from flat to dendritic growth of CaSiO3 occurs; the formation of dendritic Wollastonite is favorable at a lower Al2O3 content, a lower temperature and a higher anisotropy. When temperature increases, the transition prefers taking place at lower interface energy. Simulations also show that the tip velocity firstly increases until it reaches a maximum value and then decreases slowly with further decreasing the temperature, while the velocity only increases at a lower interfacial energy level. For anisotropy strength, its increase causes a higher tip velocity. Furthermore, validation of these parameter effects was performed by comparing the simulation results with an analytical model, showing quantitatively good agreement, when solute interaction was taken into account in the analytical model.