搅拌条件下晶体游离模型探讨

Crystal Detachment in Stirring Condition

通过对型臂晶体及枝晶臂的力学分析，提出了晶体游离的条件，进而研究了各种游离模型的适用范围。结论认为，型壁晶体及枝晶臂都可能是游离晶的来源。凝固初期，型壁晶体的机械剥离为主，后期则主要是枝晶臂游离。枝晶臂游离随流动系数的不同可以有颈缩－ 熔断和颈缩－ 折断两种模式。无颈缩枝晶臂游离在搅拌条件下也几乎是不可能的。

Through a mechanical analysis of the dendritic arm and the crystal on the mould wall,a condition of crystal detachment has been proposed in this paper.Based on the analysis and the theoretical discussion of various models of crystal detachment,the accommodation of the models has been determined.The conclusions obtained are as following:the stripping of the crystals on the mould walls is the major form in the initial period of solidification process,but the detachment of dendritic arm acts as the important role in the final stage;there are two kinds of the model of the dendritic arm detachment:necking melting and necking breaking;and the dendritic arm without necking can hardly be detached in stirring condition.