Eutectic growth in bulk undercooled melts
Eutectic growth in bulk undercooled melts
复制标题
块状过冷熔体的共晶生长
DOI：
10.1016/j.actamat.2005.01.042
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发表时间：
2005-05-01
期刊：
影响因子：
9.4
通讯作者：
Zhou, YH
中科院分区：
文献类型：
--
作者：
Li, JF;Zhou, YH
固液界面原子附着的动力学效应和热过冷被纳入对块体过冷熔体中共晶生长的分析中。当结晶产物含有金属间化合物或其他拓扑复杂相时，动力学效应将显着改变共晶生长行为，并维持耦合共晶生长至更高的过冷度。这种现象在共晶相在共晶组成下具有窄结晶温度范围的合金系统中表现得更显着。由于液体中沿生长方向存在负温度梯度，生长界面在过冷熔体中本质上是不稳定的，并且容易分解成树枝状形态。考虑到热扩散长度远大于共晶层间距，因此将共晶枝晶视为热枝晶。研究发现，共晶枝晶尖端的热过冷度随着生长速度的增大而增大，但过冷度越低，其占总过冷度的比例就越高。换句话说，在低生长速度下，热扩散对共晶生长的影响更为显着。 (c) 2005 Acta Materialia Inc. 由 Elsevier Ltd 出版。保留所有权利。
Kinetic effect of the atom-attachment at the solid-liquid interface and thermal undercooling are incorporated into the analysis of the eutectic growth in bulk undercooled melts. When crystallization products contain intermetallic compounds or other topologically complex phases, the kinetic effect will significantly alter the eutectic growth behaviors, and maintain the coupled eutectic growth to higher undercoolings. Such phenomena are exhibited more notably in alloy systems where the eutectic phases have a narrow crystallization temperature range at the eutectic composition. The growing interface is essentially unstable in the undercooled melt owing to the existence of a negative temperature gradient in the liquid along the growth direction, and tends to break down into dendritic morphology. Considering that the thermal diffusion length is much larger than the eutectic lamellar spacing, the entectic dendrite is treated as a thermal dendrite. It is found that the thermal undercooling at the eutectic dendrite tip increases with the increasing growth velocity, but its proportion of the total undercooling is higher at the lower undercoolings. In other words, the effect of the thermal diffusion on the eutectic growth is more significant at the low growth velocities. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.