Eutectic spacing and faults of directionally solidified Al–Al₃Ni eutectic

The Al–Al3Ni eutectic was directionally solidified at a thermal gradient of 4.5 K/mm in a vacuum Bridgman–type furnace in order to study eutectic spacing selection criterion.The microstructure was examined in transverse and longitudinal sections and the interrod spacings were measured at different growth velocity. It has been shown that the interrod spacing is not unique and displays a limited range for rodlike Al–Al3Ni eutectic alloy. The initial growth velocities are not responsible for the eutectic spacing range, while such faults as branching, endingand diameter change have a significant influence on the eutectic spacing adjustment.