Visualization of convective solidification in a vertical layer of eutectic Ga-In melt

A vertical layer of an eutectic gallium indium mixture was subjected to a horizontal temperature gradient. The well stirred melt was first solidified and then remelted in a slow, quasi-steady fashion. Real-time visualization of the processing is provided by radioscopy. It was observed that gravitational segregation leads to 1) a break down of convection, and 2) an early solidification of beta-indium, followed by an eutectic solidification of most of the remaining melt. The amount of observed concentrational segregation is higher than predicted by theory. The experimental findings have never been predicted in modeling efforts of similar situations including convection; possible reasons are discussed.