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基于耦合流场的Wheeler模型,采用有限差分法对纯镍枝晶生长过程进行了模拟,研究了初始晶核半径对枝晶形貌及尖端生长行为的影响,分析了初始晶核半径大于尖端分裂临界晶核半径时的枝晶生长机理。结果表明,在流速为14.76 m/s的垂直强制对流作用下,初始晶核半径小于尖端分裂临界晶核半径时,不同初始晶核半径的枝晶臂尖端生长行为相似,且为抛物线形;初始晶核半径大于尖端分裂临界晶核半径时,晶核各优先生长方向上均形成两个突起,水平方向的两个突起合并粗化形成单一枝晶臂,逆流、顺流方向的两个突起平行生长形成尖端分叉的枝晶臂。
Based on the Wheeler model of coupled flow field, the growth process of pure nickel dendrite was simulated by finite difference method. The effect of initial nucleation radius on dendritic morphology and tip growth behavior was studied. The initial nucleation radius was larger than that of tip dehiscence Dendritic Growth Mechanism at Critical Nuclei Radius. The results show that the growth of dendrite arm with different initial nuclei radius is similar and parabolic at initial flow rate of 14.76 m / s when the initial nucleus radius is smaller than the critical nuclei radius of tip split. When the radius of the nucleus is larger than the critical nucleus radius of the tip splitting, two protrusions are formed in each preferential growth direction of the nucleus. Two protrusions in the horizontal direction coalesce to form a single dendrite arm. The two protrusions in the countercurrent and downstream directions are parallel Grow to form a sharp-bifurcated dendritic arm.