1977 Volume 63 Issue 3 Pages 441-449
In the previous paper we discussed the solute distribution during dendritic growth as a function of the area fraction solidified, and suggested that the diffusion layer exists ahead of the solid-liquid interface near growing dendrite tips. In the present work, we investigated the solute distribution and the three dimensional morphology of a growing columnar dendrite in 25-20 austenitic stainless steel.
The results obtained are as follows:
1) The growth process of columnar dendrites can be classified into four stages. The growth of the secondary dendrite plates belongs to the first and the second stage of solidification. In the third and final stages dendrite substructures generally grow in the plane normal to the primary dendrite arm.
2) The area fraction solidified in the transverse section to the primary dendrite arm is nearly equivalent to the volume fraction solidified. The area fraction solidified is sufficient to explain the solute redistribution mechanism during dendritic growth.
3) A diffusion layer exsits ahead of the solid-liquid interface in the intermediate liquid region between two neighboring secondary dendrite plates, as in the case of near the growing primary dendrite tip.