Anaxial columnar dendrites in directional solidification of an Al-15 wt.% Cu alloy

A new dendrite morphology, anaxial columnar dendrites, was found in directional solidification using the real-time X-ray imaging technique. The dendrites are composed of a pair of stems, which are divided by a narrow liquid zone located in their center. The formation process of a free dendrite in the melt indicates that it grows along < 110 > directions. According to the basic morphology of the dendrites, a tip model was developed to explain the growth preference of the secondary arms. The formation of anaxial columnar dendrites indicates that the dendrite morphology is closely related to the selection of the growth direction of the dendrites. (C) 2011 Elsevier B.V. All rights reserved.