Directional dendrite growth of SCN-3wt% H₂O under shear flow

Directional solidification of SCN-3wt% H₂O was carried out under externally imposed parallel shear flow, and the growth characteristics of dendritic tips, primary arms and secondary arms were investigated. A bright band related to solute boundary layer along the dendritic tip is observed for the first time. It was confirmed that the left-right symmetry of the dendritic tip is broken up by the shear flow, with the dendritic tip tilting toward the upstream side. The tilting angle increases with the pulling rate. Compared with the case of static condition, the primary spacing becomes lager under shear flow, and this is due to the coupling effect of flow and solute fields. The growth of secondary arm is promoted at the upstream side whereas greatly restrained at the downstream side, which is caused by the circumfluence among dendrites produced by force flow.