Orientation selection in dendritic evolution
Orientation selection in dendritic evolution
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DOI：
10.1038/nmat1693
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发表时间：
2006-08-01
期刊：
影响因子：
41.2
通讯作者：
Rappaz, Michel
中科院分区：
文献类型：
--
作者：
Haxhimali, Tomorr;Karma, Alain;Rappaz, Michel
几个世纪以来，树枝状晶体的生长模式一直吸引着科学家。这些图案的美学吸引力大部分源于初级、次级和高级分支的等级结构，这些分支通常沿着沿着主晶轴生长。还观察到非典型的生长方向。在这里，我们证明了计算和实验的范围内可能的枝晶生长方向，因此所得到的树枝状结构的形态多样性，比以前预期的要丰富得多。特别是，我们表明，一次枝晶生长方向可以连续变化，在不同的结晶方向作为一个功能的组成依赖的各向异性参数。本研究结合相场法模拟Al-Zn合金的等轴枝晶生长与定向凝固。模拟和实验都表现出连续变化的方向从< 100 >到< 110 >一个潜在的立方对称性。这些结果对控制枝晶凝固的各种铸造合金的微观结构具有重要意义。
Dendritic crystal growth patterns have fascinated scientists for several centuries. Much of the aesthetic appeal of these patterns stems from the hierarchical structure of primary-, secondary-, and higher-order branches, which typically grow along principal crystallographic axes. Atypical growth directions have also been observed. Here, we demonstrate both computationally and experimentally that the range of possible dendrite growth directions, and hence the morphological diversity of the resulting dendritic structures, is much richer than previously anticipated. In particular, we show that primary dendrite growth directions can vary continuously between different crystallographic directions as a function of the composition- dependent anisotropy parameters. The study combines phase-field simulations of equiaxed dendritic growth and directional freezing of Al-Zn alloys. Both simulations and experiments exhibit continuous changes of direction from < 100 > to < 110 > for an underlying cubic symmetry. These results have important implications for controlling the microstructure of a wide range of cast alloys that solidify dendritically.