Abstract
The Zn-2mass%Al alloy installed in a tubular mold of different inner diameters (the specimen diameter) was solidified from the substrate in the temperature gradient. With decreasing specimen diameter, the transition from the planar growth to the columnar growth occurred in the shorter period during furnace cooling. However, when the specimen diameter decreased to 0.1mm, there were two transition periods: the early transition and the delayed transition. It was thought that the smaller specimen diameter restricted the perturbation behavior of the interface to change the stability condition of the interface, and caused the split of the transition period.
