采用SCN-5H_2O(摩尔分数,%)透明模型合金研究了较低剪切速率范围内过冷合金熔体中晶体的生长与演化行为.结果表明,在较大过冷度下,存在一个剪切速率阈值,当熔体剪切速率高于阈值,晶体能够以球状形态生长;当剪切速率低于阈值,晶体以枝晶形态生长.在较低剪切速率下,过冷度较大时,球晶失稳后呈枝晶形态,过冷度较小时,球晶失稳后呈玫瑰晶形态.球晶失稳形成玫瑰晶是由球晶界面扰动胞低速生长过程中尖端发生持续分叉所造成的. The growth and evolution of the crystals in the undercooled melt at a low shear rate were investigated by using a transparent model alloy of SCN-5H 2 O (mole fraction,%). The results show that there is a shear at higher undercooling When the melt shear rate is higher than the threshold value, the crystal can grow in a spherical form. When the shear rate is lower than the threshold value, the crystal grows in a dendritic form. At lower shear rates, Spherulitic instability after the dendritic morphology, when the degree of undercooling spherulites instability rose crystal morphology spherulites instability rose crystal is spherulite interface disturbance cell slow growth in the process of sustained bifurcation Caused.