Dynamics of interaction between dislocations and point defects in bcc iron

Abstract

The interaction between dislocations and point defects is crucial for many physical properties and phenomena in materials, such as strengthening mechanisms, dislocation bias and void swelling, creep, and impurity segregation around dislocations. Conventional dislocation-point defect interaction models use approximations based on elasticity theory and/or based on assumptions that transition states energies can be deduced from the binding energies of the defects. In this paper, we present the transport properties of point defects near dislocations based on the actual saddle-point configuration of vacancies and self-interstitial atoms as a function of position with respect to screw and edge dislocations in a model system (bcc iron) using the self-evolving atomistic kinetic Monte Carlo. KMC simulations reveal defect dynamics near dislocations are highly anisotropic and correlated, particularly for dumbbells in the compressive field of the edge dislocation, which could result in zones near dislocation cores where dumbbells are less efficiently absorbed compared with vacancies. This study provides accurate saddle-point configurations and energies required to properly describe the dynamics of point defects around dislocations, allowing fundamental insights on the transport mechanisms which are essential for understanding microstructural evolution and mechanical properties of metallic materials.