Abstract The 1/2 1 _ 0]{111} ordinary dislocations play an important role in the mechanical behaviors of L10 alloys. The core of this kind of dislocations has asymmetric four-fold nonplanar structure spreading onto two equivalent {111} planes, which makes the traditional planar core structure based Peierls-Nabarro (P–N) model inappropriate to describe the dislocation properties. Under this context, an improved Peierls-Nabarro (P–N) model is developed in the present work to investigate the dislocation width, stress field and Peierls stress of the ordinary 1/2 1 _ 0]{111} screw dislocation in L10 alloys (TiAl, TiGa and CuAu). This extended P–N model considers the nonplanar core structure with physical information obtained by the density functional theory (DFT) simulations. By the variational method, the corresponding dislocation equation is solved. It is found that the dislocation width of the ordinary 1/2 1 _ 0]{111} screw dislocation is as narrow as 0.5b. Compared to the results predicted for the planar core structure or the assumed Volterra dislocation, the long-range stress field induced by the real asymmetric four-fold core presents a clear rotation. When increasing the applied stress, the distribution of the Burgers vector along the four different core folds differs more and more from each other. When the applied stress attains a critical value (i.e., the Peierls stress), the dislocation core turns to be a planar structure and a fully discrete method is used to calculate the Peierls stress. Different from the original P–N model that underestimates the Peierls stress by several orders of magnitude, the Peierls stress predicted by the improved P–N model is well consistent with the previous DFT simulations. Apparently, when the long-range interaction between dislocations is taken into account for discrete dislocation simulations or theoretical analysis and when the Peierls stress is calculated for L10 alloys, the consideration of the asymmetric nonplanar core structure by the improved P–N model is necessary to have more accurate results.

中文翻译：

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L10 合金中不对称非平面 1/2<110]{111} 螺型位错的改进 Peierls-Nabarro 模型

摘要 1/2 1 _ 0]{111} 普通位错在L10合金的力学行为中起重要作用。这种位错的核心具有不对称的四重非平面结构，分布在两个等效的 {111} 平面上，这使得传统的基于平面核心结构的 Peierls-Nabarro (P-N) 模型不适用于描述位错特性。在此背景下，本工作开发了改进的 Peierls-Nabarro (P-N) 模型来研究 L10 合金中普通 1/2 1 _ 0]{111} 螺旋位错的位错宽度、应力场和 Peierls 应力(TiAl、TiGa 和 CuAu)。这种扩展的 P-N 模型考虑了具有通过密度泛函理论 (DFT) 模拟获得的物理信息的非平面核心结构。通过变分法求解相应的位错方程。发现普通1/2 1 _ 0]{111}螺位错的位错宽度窄至0.5b。与对平面核心结构或假定的沃尔泰拉位错预测的结果相比，由真正的不对称四重核心引起的长程应力场呈现出明显的旋转。当施加的应力增加时，沿四个不同核心褶皱的 Burgers 矢量分布彼此越来越不同。当外加应力达到临界值（即 Peierls 应力）时，位错核变为平面结构，采用完全离散的方法计算 Peierls 应力。与将 Peierls 应力低估几个数量级的原始 P-N 模型不同，改进的 P-N 模型预测的 Peierls 应力与之前的 DFT 模拟非常一致。显然，当离散位错模拟或理论分析考虑到位错之间的长程相互作用以及计算 L10 合金的 Peierls 应力时，改进 P-N 模型考虑非对称非平面核结构是必要的有更准确的结果。