Abstract Tip velocities of undercooled dendrites in electromagnetically levitated melt droplets of pure Ti were modeled using a theory on three-dimensional dendritic growth with fluid flow and a dilute solute. The modeling shows that a forced flow due to electromagnetic stirring depresses tip velocities of the dendrites at low undercoolings and that its effect becomes negligible at high undercoolings. In contrast, an oxygen impurity dissolved in liquid Ti depresses tip velocities of the dendrites over a broad range of undercooling while it coarsens tip radii. Such modeling results allowed for reconciliation of discrepancies in literature data by considering an oxygen impurity effect. The modeling also predicts that the effect of the oxygen impurity becomes insignificant when its concentration is reduced below 50 ppm in atomic fraction.

中文翻译：

---

考虑强制流动和氧杂质效应的过冷钛枝晶尖端动力学建模

摘要 利用流体流动和稀溶质的三维枝晶生长理论，对纯钛电磁悬浮熔滴中过冷枝晶的尖端速度进行了建模。建模表明，电磁搅拌导致的强制流动在低过冷度下会降低枝晶的尖端速度，而在高过冷度下其影响可以忽略不计。相比之下，溶解在液态钛中的氧杂质会在广泛的过冷范围内降低枝晶的尖端速度，同时使尖端半径变粗。通过考虑氧杂质效应，这样的建模结果允许协调文献数据中的差异。该模型还预测，当氧杂质的浓度降低到原子分数 50 ppm 以下时，其影响将变得微不足道。