A phase field model for dislocations in hexagonal close packed crystals
A phase field model for dislocations in hexagonal close packed crystals
复制标题
DOI：
10.1016/j.jmps.2019.103823
复制
发表时间：
2020-04
影响因子：
5.3
通讯作者：
C. Albrecht;A. Hunter;A. Kumar;I. Beyerlein
中科院分区：
文献类型：
--
作者：
C. Albrecht;A. Hunter;A. Kumar;I. Beyerlein
在这项工作中，应用相场公式适合于模拟运动的个别部分和全部位错在六方密排（HCP）晶体。该配方采用了周期性的潜力，滑翔在不同的HCP滑移系统，这是在这里通知密度泛函理论（DFT）。该模型被应用到模拟的解离过程中开始从一个不稳定的完美的位错，并在其最终的平衡结构为不同的滑移面和不同的HCP金属结束。预测这些位错的结构特征包括偏伯格斯矢量，离解距离，偏芯宽度，以及这些量的任何不对称性。镁被选为模型材料之一，因为它的位错是最好的研究，它几乎是弹性各向同性。对于镁，它示出的离解距离的预测同意与先前报道的原子尺度计算，包括密度泛函理论，位错的基础上< a >，棱柱< a >形，金字塔型II滑移系。此外，相场模型的结果也提出了在Ti和Zr的位错，我们发现开发明显不同的平衡结构比Mg。
In this work, an application of a phase field formulation suitable for modeling the motion of individual partial and full dislocations in hexagonal close packed (HCP) crystals is presented. The formulation incorporates periodic potentials for glide on the distinct HCP slip systems, which are informed here by density functional theory (DFT). The model is applied to simulate the dissociation process starting from an unstable perfect dislocation and ending at its final equilibrium structure for different slip planes and in different HCP metals. The structural characteristics that are predicted for these dislocations include the partial Burgers vectors, dissociation distances, core widths of the partials, and any asymmetries in these quantities. Mg is selected as one of the model materials since its dislocations are the most well studied and it is nearly elastically isotropic. For Mg, it is shown that the predictions for dissociation distances agree with those reported previously by atomic-scale calculations, including density functional theory, for dislocations on the basal < a >, prismatic < a >, and pyramidal type II slip systems. Furthermore, phase field model results are also presented for dislocations in Ti and Zr, which we find develop distinctively different equilibrium structures than Mg.