Modeling rapid solidification of multi-component concentrated alloys

A sharp interface model for rapid solidification of multi-component concentrated alloys was developed based on the thermodynamic extremal principle and extended irreversible thermodynamics. The evolution path of the system, including diffusion in the bulk phases and the contact conditions at the interface, was determined in which local non-equilibrium effects, both in the bulk phases and at the interface, were considered. Applying the present model, a comparative study with the model of Ludwig (Physica D 1998;124:271) was performed to show the kinetics of the steady-state interface. Due to correlations among different components in the concentrated solutions, the partition coefficients of certain alloys are predicted to change non-monotonically with interface velocity, accompanied with a significant lowering of the interface temperature. Combining the non-steady-state interface conditions with the present model and the model of Ludwig, the non-equilibrium transients after temperature perturbation were studied to show the evolution of the interface conditions, where the quasi-steady-states are reached after a very short time span (10^-10 s).