Rapid dendritic growth of Al-Ge hypoeutectic alloy in a drop tube

Dendritic growth in A1-45 % Ge hypoeutectic alloy has been investigated during free fall in a 3 m drop tube. Calculations indicate that the undercooling obtained for the falling A1-45% Ge droplets ranges from 13K to 201 K. The maximum undercooling attains 0. 27TL- With the increase of undercooling, the primary (A1) phase undergoes a "columnar dendrite to equiaxed dendrite" structural transition. According to the current rapid dendritic growth theory, the growth of primary (Al) phase is always controlled by solute diffusion.