The Effect of Melt Flow on the Dendrite Morphology

The anisotropy of dendritic structure is characterized in this paper. The direction of move of liquid/solid interface influence the velocity of the melt flow. In the course of the experiments the liquid/solid interface was moved in three different directions: i) at right angles to the direction of gravity vector, ii) in the direction identical with it and iii) in the direction opposite to it. Our purpose was to investigate the shape of solidifying dendrites as a function of the angle included by the gravity vector and solidification [6]. The measurements were done in real images fixed by us. The following parameters were chosen for characterizeing the anisotropy of dendrites: intersection number of the test lines and dendrite interface (P), orientation factor (
), dendritic surface in volume (SV). The material was solidified by using an equipment developed by the authors. The solidification rate is a constant value: 0.001 mm/s and 0.003 mm/s, the composition of material used for modelling purposes is: SCN (succinonitrile) -2.5-3 mass% of acetone. 100 images were processed in each direction. It was necessary to rotate the images in order to count the number of intersections. A program developed by the authors was used for this purpose; the number of intersections was given by the program as a function of the angle of rotation, and the perimeter and area of the dendrites.