FLOW PHENOMENA OF MUSHY ZONE CAUSED BY SU CTION AND FORMATION MECHANISM OF V-TYPE SEGREGATION

In order to clarify the formation mechanism of V-type segregation, flo w phenomena was examined by using two kinds of samples : solid particl e-water mixture and aqueous solution of NH4Cl. The former was used to simulate the slipping phenomena oi equiaxed crystals in the mushy zone and the latter to simulate the remelting of mushy zone of ingot. Thes e samples were sucked down through the outlet located at the center of the bottom of a cavity with constant velocities, which is called arti ficial suction. Most particles or equiaxed crystals and liquid in the upper part oi the cavity moved down vertically. The V-type movement or slipping of particles were not observed. In the case of aqueous solut ion oi NH4Cl, equiaxed crystals moved down vertically during the artif icial suction and the V-type movement or slipping were not observed. H owever, the V-type segregation were formed in the mushy zone. It is co ncluded that the V-type segregation were not formed by the slipping ph enomena but by the remelting.