Phase-field study of competitive dendritic growth of converging grains during directional solidification
Phase-field study of competitive dendritic growth of converging grains during directional solidification
复制标题
定向凝固过程中会聚晶粒竞争枝晶生长的相场研究
DOI：
10.1016/j.actamat.2011.11.037
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发表时间：
2012-02-01
期刊：
影响因子：
9.4
通讯作者：
Wang, Jincheng
中科院分区：
文献类型：
--
作者：
Li, Junjie;Wang, Zhijun;Wang, Jincheng
用相场法研究了定向凝固过程中不同取向晶粒的组织演变。对于会聚的枝晶，除了通常被接受的过度生长模式外，在我们的模拟中也发现了最近一些实验中观察到的相反的过度生长模式，其中有利取向的枝晶阻止了不利取向的枝晶。分析了可能导致这种异常过度生长的因素。结果表明，除了尖端过冷度的差异外，在经典理论模型中被忽略的收敛枝晶间的溶质相互作用对低拉速下过生长的本质也有显著影响。溶质相互作用可以延缓晶界枝晶的生长，并导致这些枝晶相对于其邻近枝晶的生长滞后，这使得不利取向的枝晶有可能过度生长有利取向的枝晶。然而，只有当有利取向的GB枝晶与其直接有利取向的相邻枝晶之间的间距通过横向运动减小到一定水平时，这种异常的过度生长才会发生。这些发现可以拓宽我们对枝晶聚集的过度生长机制的理解。(C)2011 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
The microstructure evolution of grains with different orientations during directional solidification is investigated by the phase-field method. For converging dendrites, in addition to the usually accepted overgrowth pattern wherein the favorably oriented dendrites block the unfavorably oriented ones, the opposite pattern of overgrowth observed in some recent experiments is also found in our simulations. The factors which may induce this unusual overgrowth are analyzed. It is found that in addition to the difference in tip undercooling, the solute interaction of converging dendrites, which has been ignored in the classical theoretical model, also has a significant effect on the nature of the overgrowth at low pulling velocities. Solute interaction can retard the growth of dendrites at the grain boundary (GB) and induce a lag of these dendrites relative to their immediate neighbors, which gives the unfavorably oriented dendrite the possibility to overgrow the favorably oriented one. However, this unusual overgrowth only occurs when the spacing between the favorably oriented GB dendrite and its immediate favorably oriented neighbor decreases to a certain level through lateral motion. These findings can broaden our understanding of the overgrowth mechanism of converging dendrites. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.