An experimental investigation on the kinetics of solute driven remelting

The present study is aimed at understanding the interface kinetics during s olute driven remelting in metallic alloys. Solid Al is placed in contact wi th a liquid Al Mg alloy. As solid and liquid compositions at the interface are out of equilibrium, remelting takes place. The remelting rate is estima ted as a function of time using a simple heat balance. The estimated veloci ty from the heat-balance calculations shows excellent agreement with the ge ometric velocity, directly measured from the remelted samples in each exper iment. This confirms the accuracy and reliability of the heat-balance calcu lations and establishes this technique as a potential method for tracing th e interface velocity during remelting. The results indicate that, at a cons tant temperature, an increase in liquid supersaturation leads to a linear i ncrease in remelting velocity, as a result of an increasing driving force f or remelting. At a constant liquid supersaturation, an increase in temperat ure results in an exponential increase in the remelting velocity, due to th e enhanced mass transport at the higher temperatures. Semi-empirical relati ons are derived from these experimental observations and a combined analysi s of the effects of driving force and kinetics yields a relation for remelt ing velocity as a function of temperature for a variety of boundary conditi ons. Remelting velocities predicted by this relation are in good agreement with the experimental observations.