THE TRANSITION FROM SHORT-RANGE DIFFUSION-LIMITED TO COLLISION-LIMITED GROWTH IN ALLOY SOLIDIFICATION
THE TRANSITION FROM SHORT-RANGE DIFFUSION-LIMITED TO COLLISION-LIMITED GROWTH IN ALLOY SOLIDIFICATION
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DOI：
10.1016/0956-7151(94)90507-x
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发表时间：
1994-02-01
期刊：
影响因子：
--
通讯作者：
BOETTINGER, WJ
中科院分区：
文献类型：
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作者：
AZIZ, MJ;BOETTINGER, WJ
短程扩散限制生长，碰撞限制生长，以及两种制度之间的过渡被解释为合金凝固动力学的单一模型的自然结果;推导了稀相合金凝固过程中平面界面速度-过冷度函数的解析表达式，使用Turnbull的碰撞限制增长模型和Aziz和Kaplan的连续增长溶质捕获模型，有和没有溶质阻力效应。的界面迁移率，-dv/dT，被证明是非常高的（正比于声速），如果合金是足够稀释的，或者如果生长速度是足够快的几乎完全的溶质捕获。界面迁移率降低约三个数量级（成为成比例的扩散速度）在中间生长速率，其中发生部分溶质捕获。在低速度预测模型和无溶质阻力的差异进行了讨论。Al-Be合金的非稀动力学模型的解析表达式的数值解的结果的比较表明，稀近似分解在10原子%的顺序上的熔体组成。界面迁移率的类似变化示出了Boettinger和Aziz的无序捕获模型。
Short-range diffusion-limited growth, collision-limited growth, and the transition between the two regimes are explained as natural consequences of a single model for the kinetics of alloy solidification; Analytical expressions are developed for the velocity-undercooling function of a planar interface during dilute alloy solidification, using Turnbull's collision-limited growth model and the Continuous Growth Solute Trapping Model of Aziz and Kaplan both with and without a solute drag effect. The interface mobility, -dv/dT, is shown to be very high (proportional to the speed of sound) if the alloy is sufficiently dilute or if the growth rate is sufficiently rapid for nearly complete solute trapping. The interface mobility is reduced by about three orders of magnitude (becoming proportional to the diffusive speed) at intermediate growth rates where partial solute trapping occurs. Differences in low velocity predictions of the models with and without solute drag are also discussed. Comparison of the results of the analytical expressions to numerical solutions of the non-dilute kinetic model for Al-Be alloys shows that the dilute approximation breaks down at melt compositions on the order of 10 at.%. Similar variations in the interface mobility are shown for the disorder-trapping model of Boettinger and Aziz.