The core structure and recombination energy of a copper screw dislocation: a Peierls study

Journal Article · Fri May 19 00:00:00 EDT 2017 · Philosophical Magazine (2003, Print)

DOI:https://doi.org/10.1080/14786435.2017.1328138· OSTI ID:1369196

Szajewski, B. A. ^[1]; Hunter, A. ^[1]; Beyerlein, I. J. ^[2]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2. Univ. of California, Santa Barbara, CA (United States)

The recombination process of dislocations is central to cross-slip, and transmission through Σ3 grain boundaries among other fundamental plastic deformation processes. Despite its importance, a detailed mechanistic understanding remains lacking. In this paper, we apply a continuous dislocation model, inspired by Peierls and Nabarro, complete with an ab-initio computed -surface and continuous units of infinitesimal dislocation slip, towards computing the stress-dependent recombination path of both an isotropic and anisotropic Cu screw dislocation. Under no applied stress, our model reproduces the stacking fault width between Shockley partial dislocations as predicted by discrete linear elasticity. Upon application of a compressive Escaig stress, the two partial dislocations coalesce to a separation of ~|b|. Upon increased loading the edge components of each partial dislocation recede, leaving behind a spread Peierls screw dislocation, indicating the recombined state. We demonstrate that the critical stress required to achieve the recombined state is independent of the shear modulus. Rather the critical recombination stress depends on an energy difference between an unstable fault energy (γτ) and the intrinsic stacking fault energy (γτ-γisf). We report recombination energies of ΔW = 0.168 eV/Å and ΔW = 0.084 eV/Å, respectively, for the Cu screw dislocation within isotropic and anisotropic media. Finally, we develop an analytic model which provides insight into our simulation results which compare favourably with other (similar) models.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE Laboratory Directed Research and Development (LDRD) Program
• Contributing Organization: Univ. of California, Santa Barbara, CA (United States)
• Grant/Contract Number: AC52-06NA25396
• OSTI ID: 1369196
• Report Number(s): LA-UR-17-20638
• Journal Information: Philosophical Magazine (2003, Print), Vol. 97, Issue 25; ISSN 1478-6435
• Publisher: Taylor & Francis
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
cross-slip
anisotropy
Peierls-Nabarro model