An experimental investigation on the kinetics of solute driven remelting

Abstract

The present study is aimed at understanding the interface kinetics during solute driven remelting in metallic alloys. Solid Al is placed in contact with a liquid Al-Mg alloy. As solid and liquid compositions at the interface are out of equilibrium, remelting takes place. The remelting rate is estimated as a function of time using a simple heat balance. The estimated velocity from the heat-balance calculations shows excellent agreement with the geometric velocity, directly measured from the remelted samples in each experiment. This confirms the accuracy and reliability of the heat-balance calculations and establishes this technique as a potential method for tracing the interface velocity during remelting. The results indicate that, at a constant temperature, an increase in liquid supersaturation leads to a linear increase in remelting velocity, as a result of an increasing driving force for remelting. At a constant liquid supersaturation, an increase in temperature results in an exponential increase in the remelting velocity, due to the enhanced mass transport at the higher temperatures. Semi-empirical relations are derived from these experimental observations and a combined analysis of the effects of driving force and kinetics yields a relation for remelting velocity as a function of temperature for a variety of boundary conditions. Remelting velocities predicted by this relation are in good agreement with the experimental observations.