Efficiency of dislocations as sinks of radiation defects in fcc copper crystal
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ICAL PROPERTIES OF CRYSTALS
Efficiency of Dislocations as Sinks of Radiation Defects in Fcc Copper Crystal A. B. Sivak and P. A. Sivak National Research Centre “Kurchatov Institute”, pl. Akademika Kurchatova 1, Moscow, 123182 Russia email: [email protected] Received November 8, 2012
Abstract—The sink efficiency of perfect dislocations for selfpoint defects (interstitials and vacancies) in fcc copper crystal has been calculated by the kinetic Monte Carlo method in a temperature range of 293–1000 K and a range of dislocation densities from 1.3 × 1012 to 3.0 × 1014 m–2. Screw, mixed, and edge dislocations with a Burgers vector 1/2〈110〉 in different slip systems are analyzed. The interaction energies of selfpoint defects with dislocations are calculated using the anisotropic theory of elasticity. Analytical expressions are proposed for the dependences of the calculated values of dislocation sink efficiency on temperature and dis location density. DOI: 10.1134/S1063774514030183
INTRODUCTION Elastic fields of dislocations, being the main sources of internal stress in crystals, significantly affect the kinetic behavior of selfpoint defects (selfintersti tial atoms (SIAs) and vacancies), including their diffu sion and absorption by dislocations. These processes depend on the crystal symmetry, elastic anisotropy, and type of defects (elastic dipoles) [1–3]; they deter mine the behavior of the microstructure and proper ties of materials under external effects of different natures (mechanical, thermal, and radiative). The main complexity in determining the disloca tion sink efficiency (DSE) in real anisotropic crystals is the consideration of the interaction between sinks and selfpoint defects (SPDs), because the configura tions of absorbed defects (their stable and saddle point configurations) have different point symme tries, as determined by the crystallographic class of crystal [4]. In most cases the DSEs are calculated in isotropic approximations (isotropic theory of elastic ity, spherical symmetry of all defect configurations [1, 5]), or their value is set a priori [6–8]. These approximations eliminate qualitative differences between crystals belonging to different crystallo graphic classes (bcc, fcc, hcp), as well as the types of dislocations and point defects (elastic dipoles). In addition, metals (especially those having an fcc struc ture) are generally crystals with high elastic anisot ropy; hence, they should be studied taking into account this factor [9]. The elastic anisotropy param eter Ael = 2C44/(C11 – C12), where C11, C12, and C44 are elastic constants, always differs from unity for fcc met als (Ael = 1 in the isotropic case). For copper, Ael = 3.25 at room temperature [10].
In this paper we report the results of studying the influence of interactions between SPDs and perfect straightline edge, screw, and mixed dislocations with Burgers vector 1/2〈110〉 on the DSEs for SPDs depending on the dislocation density (1.3 × 1012–3.0 × 1014 m–2) and temperature (293–1000 K) in fcc cop per cr
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