Theoretical Analysis and Model Study on the Structure of A-type Segregation

Abstract

Concerning the formation of macrosegregation in ingots, it is well known that the channels are smooth on the side facing the outside of ingot and rough on the side facing the inside of ingot.
In this work, these phenomena were reproduced by the model experiments using NH₄Cl-H₂O system and the progression of channel formation was precisely visualized. The experiment indicated that the channels were melted on the side facing the outside of ingot and solidified on the other side, and that the interdendritic liquid flowed into the channels through the wall facing the inside of ingot and a part of the liquid flowed out the channels through the other wall. The difference in the roughness between both walls is theoretically explained on the basis of transport phenomena in this paper.