Periodical oscillating interface in directional growth under shear flow  

作　　者：WANG JianYuan CHEN ChangLe ZHAI Wei JIN KeXin 

机构地区：[1]School of Science, Northwestern Polytechnical University, Xi'an 710072, China

出　　处：《Chinese Science Bulletin》2009年第23期4432-4437,共6页

基　　金：Supported by the National Natural Science Foundation of China (Grant Nos. 50331040 and 50702046);Science-Technology Innovation Foundation of Northwestern Polytechnical University (Grant No.2008KJ02031)

摘　　要：Liquid-solid interface morphological evolution of SCN-2wt%H2O alloy was investigated in the presence of shear flow. It has been found that shear flow strikingly enhances the stability of planar interface at lower pulling rates. In the intermediate range of pulling rate, the interface experiences periodical oscillating "planar-cellular" and "cellular-dendritic" growth patterns. The formation of oscillating growth modes can be explained by two reasons: (i) The stabilizing effect induced by shear flow competes with the growing destabilizing effect by the increase of pulling rate, which provides the driving force for morphological evolution; and (ii) the establishment of stable solute field at the liquid-solid interface needs a period of time, leading to the result that the interface evolution can not stay stable at the equilibrium state. However, as the puling rate becomes higher, it plays more and more important roles in pattern selection and dendritic growth forms.Liquid-solid interface morphological evolution of SCN-2wt%H2O alloy was investigated in the presence of shear flow. It has been found that shear flow strikingly enhances the stability of planar interface at lower pulling rates. In the intermediate range of pulling rate, the interface experiences periodical oscillating ＂planar-cellular＂ and ＂cellular-dendritic＂ growth patterns. The formation of oscillating growth modes can be explained by two reasons： （i） The stabilizing effect induced by shear flow competes with the growing destabilizing effect by the increase of pulling rate, which provides the driving force for morphological evolution; and （ii） the establishment of stable solute field at the liquid-solid interface needs a period of time, leading to the result that the interface evolution can not stay stable at the equilibrium state. However, as the puling rate becomes higher, it plays more and more important roles in pattern selection and dendritic growth forms.

关 键 词：周期性振荡 液固界面 剪切流 定向生长 界面稳定性 形态演变 增长模式 提拉速度 

分 类 号：O357.52[理学—流体力学] TN253[理学—力学]