Wang Lei, Hoyt Jeffrey J, Wang Nan, Provatas Nikolas, Sinclair Chad W
Department of Materials Engineering, The University of British Columbia, 309-6350 Stores Road, Vancouver, BC, V6T 1Z4, Canada.
Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education, School of Science, Northwestern Polytechnical University, 710072, Xi'an, China.
Nat Commun. 2020 Feb 5;11(1):724. doi: 10.1038/s41467-020-14530-7.
Although the anisotropy of the solid-liquid interfacial free energy for most alloy systems is very small, it plays a crucial role in the growth rate, morphology and crystallographic growth direction of dendrites. Previous work posited a dendrite orientation transition via compositional additions. In this work we examine experimentally the change in dendrite growth behaviour in the Al-Sm (Samarium) system as a function of solute concentration and study its interfacial properties using molecular dynamics simulations. We observe a dendrite growth direction which changes from [Formula: see text] to [Formula: see text] as Sm content increases. The observed change in dendrite orientation is consistent with the simulation results for the variation of the interfacial free energy anisotropy and thus provides definitive confirmation of a conjecture in previous works. In addition, our results provide physical insight into the atomic structural origin of the concentration dependent anisotropy, and deepen our fundamental understanding of solid-liquid interfaces in binary alloys.
尽管对于大多数合金体系而言，固 - 液界面自由能的各向异性非常小，但它在枝晶的生长速率、形态以及晶体生长方向方面起着至关重要的作用。先前的研究提出通过成分添加实现枝晶取向转变。在这项工作中，我们通过实验研究了Al - Sm（钐）体系中枝晶生长行为随溶质浓度的变化，并使用分子动力学模拟研究其界面性质。我们观察到随着Sm含量的增加，枝晶生长方向从[公式：见原文]变为[公式：见原文]。观察到的枝晶取向变化与界面自由能各向异性变化的模拟结果一致，从而为先前工作中的一个猜想提供了确凿的证实。此外，我们的结果为浓度依赖性各向异性的原子结构起源提供了物理见解，并加深了我们对二元合金中固 - 液界面的基本理解。
