EFFECT OF LIQUID FLOW ON PRIMARY ARM SPACINGS OF CONSTRAINED COLUMNAR CRYSTALS
液相流动对柱晶一次间距的影响

An experimental apparatus, which has a convection generator and anaid-heater, is developed for the study of the effect of stable laminar liquid flow on thedirectional solidification process by the use of transparent alloy SCN-2wt-% Ace. The flowis perpendicular to primary arms. By,in-situ observation and photographing at different spe-cific moments, it has been found that such a flow can cause a great change in primaryspacings of constrained columnar crystals: for cells, the spacings become smaller; but fordendrites, they become larger. The former is mainly due to the tilted growth of upstreamsidebranches, while the latter is mainly due to the coupling effect of liquid flow with solutal fieldaround dendrite tips. The faster the liquid flows, the further smaller the cells space and thefurther larger the dendrites space.