Computer simulations of vacancy and interstitial interactions with the (a/2) 〈110〉 edge dislocation in copper

Abstract

All simulations are performed with a single interatomic potential, the general features of which are outlined in a paper by Johnson. Analyses of a vacancy, an interstitial, and a stable (a/2) 〈110〉 edge dislocation in copper are presented, along with calculations each describing a vacancy and an interstitial in static equilibrium at the edge of the dislocation. Vacancy and interstitial formation energies and associated strain patterns are calculated. The 〈100〉 split interstitial configuration is stable with a formation energy of 3.060 eV. The vacancy formation energy is 1.165 eV. The strain patterns agree well with those obtained by others. The (a/2) 〈110〉 edge dislocation on the {111} plane is positioned in the lattice according to a previously devised procedure which results in complete agreement between atomistic and continuum treatments in regions of small strain. Atomic displacements parallel to the dislocation line are analyzed and their variation with distance from the line is shown to be oscillatory and to damp out within about 9 Å of the line. The over-all significance of such displacements to dislocation core simulation is discussed. The core radius and energy are calculated to be 4.8 Å and 0.278 eV per (112) plane, respectively, and the core configuration is shown to be consistent with the short-range character of the potential. A lattice with 4080 atoms on 24 (112) planes is used to analyze the point-defect-dislocation interactions. With regard to a vacancy or an interstitial at the edge of the dislocation, each is bound to the dislocation having binding energies 0.247 and 0.800 eV, respectively. The atomic configuration and strain pattern associated with each bound defect are presented.