Interface kinetics modeling of binary alloy solidification by considering correlation between thermodynamics and kinetics

By considering collision-limited growth mode and short-range diffusion-limited growth mode simultaneously, an extended kinetic model for solid−liquid interface with varied kinetic prefactor was developed for binary alloys. Four potential correlations arising from effective kinetics coupling the two growth modes were proposed and studied by application to planar interface migration and dendritic solidification, where the linear correlation between the effective thermodynamic driving force and the effective kinetic energy barrier seems physically realistic. A better agreement between the results of free dendritic growth model and the available experiment data for Ni−0.7at.%B alloy was obtained based on correlation between the thermodynamics and kinetics. As compared to previous models assuming constant kinetic prefactor, a common phenomenon occurring at relatively low undercoolings, i.e. the interface migration slowdown, can be ascribed to both the thermodynamic and the kinetic factors. By considering universality of the correlation between the thermodynamics and kinetics, it is concluded that the correlation should be considered to model the interface kinetics in alloy solidification.