论文标题
运输机制对双连续结构块化的影响：散装与表面扩散之间的比较
Effect of Transport Mechanism on the Coarsening of Bicontinuous Structures: A Comparison between Bulk and Surface Diffusion
论文作者
论文摘要
在多种系统中观察到了双连续微结构的变色，例如纳米孔金属和具有旋转分解的混合物。为了更好地理解这些结构在变高过程中的形态演变，我们比较了两种不同的粗化机制，表面和散装扩散所产生的形态。我们以每种机制在两相混合物中进行浓缩的相位模拟，以标称体积分数为50％-50％和36％-64％，并以拓扑（属密度），室间形状分布，结构因子和相位和平均曲率的自相关性来表征模拟结构。我们观察到形态和拓扑的自相似演化，并与预期的动态缩放能力定律达成一致，其中特征长度尺度随时间缩小与表面扩散的$ t^{1/4} $成比例地增加，而$ t^{1/3} $用于散装扩散。虽然我们观察到更高的动力学的预期差异，但我们发现，由于浓缩机制而引起的自相似形态的差异相对较小，尽管通常它们在36％的体积分数中大于50％的体积分数。特别是，我们发现通过表面扩散使属的缩放属密度比通过大量扩散块的结构较低。我们还将自相似的形态与文献中的形态和两个模型的双连续结构进行了比较，即基于Schoen g最小的表面和随机水平的波结构的恒定均值外表面。这些模型结构的平均缩放平均曲率与36％和50％的粗糙结构的平均平均曲率一致，但我们发现缩放属密度和平均曲率的标准偏差存在实质性分歧。
Coarsening of bicontinuous microstructures is observed in a variety of systems, such as nanoporous metals and mixtures that have undergone spinodal decomposition. To better understand the morphological evolution of these structures during coarsening, we compare the morphologies resulting from two different coarsening mechanisms, surface and bulk diffusion. We perform phase-field simulations of coarsening via each mechanism in a two-phase mixture at nominal volume fractions of 50%-50% and 36%-64%, and the simulated structures are characterized in terms of topology (genus density), the interfacial shape distribution, structure factor, and autocorrelations of phase and mean curvature. We observe self-similar evolution of morphology and topology and agreement with the expected power laws for dynamic scaling, in which the characteristic length scale increases over time proportionally to $t^{1/4}$ for surface diffusion and $t^{1/3}$ for bulk diffusion. While we observe the expected difference in the coarsening kinetics, we find that differences in self-similar morphology due to coarsening mechanism are relatively small, although typically they are larger at 36% volume fraction than at 50% volume fraction. In particular, we find that bicontinuous structures coarsened via surface diffusion have lower scaled genus densities than structures coarsened via bulk diffusion. We also compare the self-similar morphologies to those in literature and to two model bicontinuous structures, namely, constant-mean-curvature surfaces based on the Schoen G minimal surface and random leveled-wave structures. The average scaled mean curvatures of these model structures agree reasonably with those of the coarsened structures at both 36% and 50%, but we find substantial disagreements in the scaled genus densities and the standard deviations of mean curvature.
