In-situ investigation of the solidification dynamics in an irregular eutectic alloy

Abstract We present an in-situ experimental investigation of irregular eutectic growth dynamics observed optically in real time during directional solidification (DS) and rotating (RDS) a model transparent alloy, namely Amino-methyl-propanediol-Succinonitrile (AMPD-SCN). The SCN-rich solid grows with nonfaceted solid-liquid interface, while AMPD forms thin whisker-like faceted crystals. With RDS, we simultaneously four distinct along the front thanks to rotation induced velocity ramp. At low velocity, crystals grow individually, their leading tip ahead – at higher temperature than SCN-liquid interface which presents linear undercooling change V This regime is defined as quasi-steady decoupled growth. During are found rotate sample this regime. When they can reach unsteady coupled-growth V, since increasing favors formation AMPD-SCN-liquid trijunctions, start branch noncrystallographically. impurity effects lead two-phase fingers. Further increase results primary SCN dendrites fine interdendritic microstructure. DS experiments confirmed existence those regimes different velocities.