The Effect of Convective Instability on Coupled Growth of Hypermonotectic Alloys

The purpose of this investigation is to study the role of convection on the ability to achieve and maintain coupled growth and the formation of an aligned fibrous microstructure during directional solidification of hypermonotectic alloys. Composition variations resulting from convective mixing in the liquid are shown for hypermonotectic Al-In samples processed under both unit gravity and alternating gravity level conditions. These composition variations are compared with those expected theoretically. Theoretical composition variations are determined using an analysis designed for off-eutectic coupled growth in the presence of convection. (Author)