Grain rotation and coupled grain boundary motion in two-dimensional binary hexagonal materials
Grain rotation and coupled grain boundary motion in two-dimensional binary hexagonal materials
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DOI：
10.1016/j.actamat.2021.117583
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发表时间：
2021-12
期刊：
影响因子：
9.4
通讯作者：
Brendon Waters;Zhilong Huang
中科院分区：
文献类型：
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作者：
Brendon Waters;Zhilong Huang
晶粒演化和生长的动力学机制在控制大尺度多晶材料的结构特性方面具有根本的重要性，但是多组分材料系统中的晶格有序和不同原子种类的影响仍然没有得到很好的理解。我们研究这些影响通过相场晶体建模嵌入弯曲晶粒在二维六方晶系材料，通过检查和比较的结果，晶粒旋转，收缩，和晶界动力学在整个范围内的取向差的二元系统的六方氮化硼和单组分石墨烯单层。计算晶粒半径和取向差角之间的关系在时间演化过程中揭示了正常切向耦合运动的晶界匹配的Cahn-Taylor公式，以及过渡到滑动和政权的晶粒运动没有旋转。双组分亚晶格有序的关键作用被确定，表现为一个双重行为的正和负的耦合模式与晶粒旋转的增加和减少的角度，这是在二维单组分系统中不存在。相应的机制是超越了纯粹的几何考虑，并需要从异质元素和同质元素原子键合之间的差异，以及随后的各种各样的缺陷核心结构和转换的可用性充满活力的贡献。这表明晶格反转对称性破缺在二元或多组分材料中所起的重要作用，与单组分材料相比，导致晶界处的详细微观结构和位错缺陷动力学的变化。
The dynamical mechanisms underlying the grain evolution and growth are of fundamental importance in controlling the structural properties of large-scale polycrystalline materials, but the effects of lattice ordering and distinct atomic species in multi-component material systems are still not well understood. We study these effects through the phase field crystal modeling of embedded curved grains in two-dimensional hexagonal materials, by examining and comparing the results of grain rotation, shrinking, and grain boundary dynamics over the full range of misorientation in binary systems of hexagonal boron nitride and single-component graphene monolayers. Calculations of the relation between grain radius and misorientation angle during time evolution reveal the normal-tangential coupled motion of the grain boundary matching the Cahn-Taylor formulation, as well as the transition to sliding and the regime of grain motion without rotation. The key effect of two-component sublattice ordering is identified, showing as a dual behavior of both positive and negative coupling modes with grains rotating towards increasing and decreasing angles, which is absent in two-dimensional single-component systems. The corresponding mechanisms are beyond the purely geometric considerations and require the energetic contribution from the difference between heteroelemental and homoelemental atomic bondings and the subsequent availability of a diverse variety of defect core structures and transformations. This indicates the important role played by the lattice inversion symmetry breaking in binary or multi-component materials, causing the change of detailed microstructures and dynamics of dislocation defects at grain boundaries as compared to single-component materials.