Non-singular descriptions of dislocation cores:: a hybrid ab initio continuum approach

被引:17
作者
Banerjee, S.
Ghoniem, N. [1 ]
Lu, G.
Kioussis, N.
机构
[1] Univ Calif Los Angeles, Dept Aerosp & Mech Engn, Los Angeles, CA 90095 USA
[2] St Louis Univ, Engn Technol Dept, St Louis, MO 63103 USA
[3] Calif State Univ Northridge, Dept Phys, Northridge, CA 91330 USA
基金
美国国家科学基金会;
关键词
D O I
10.1080/14786430701528739
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
The core structure of straight and curved dislocations is studied by developing a hybrid approach that links the parametric dislocation dynamics method with ab initio calculations. The approach is an extension of the Peierls-Nabarro (PN) model, with the following features: (1) all three components of the displacement vector for atoms within the dislocation core are included; (2) the entire generalized stacking fault energy surface (GSFS) obtained from ab initio calculations is utilized; and (3) the method is generalized to treat curved dislocations. We combine the parametric dislocation dynamics (DD) approach for the interaction and motion of dislocations with ab initio calculations of lattice restoring forces. These forces, which are extracted from the GSFS (gamma-surface), are calculated from both first-principles density functional theory (DFT) and the embedded-atom method (EAM). Dislocation core structures in aluminium and silver are determined. For straight dislocations, the results from the model are shown to be in excellent agreement with experiments for both Al and Ag. In contrast to undissociated dislocation loops in Al, it is found that the core width and the separations between partials in Ag vary along the angular direction measured with respect to the Burgers vector. It is also shown that the core-cutoff radius, which is usually employed in DD calculations to avoid singularities, must be adjusted as a function of loop size to account for the correct dislocation core energy.
引用
收藏
页码:4131 / 4150
页数:20
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