Molecular static simulation of edge dislocation core in bcc iron

A A Gusev,A V Nazarov

doi:10.1088/1757-899x/1005/1/012027

Abstract

We simulate the dislocation core structure in bcc iron using the modified Molecular Static method. A feature of this method is the application of an iterative procedure in which the atomic structure in the vicinity of the defect and the constants that determine the displacements of atoms immersed in the elastic continuum are calculated in a self-consistent manner. Following the mentioned approach, we develop a model for calculating the atomic structure of edge dislocations, taking into account the anisotropy of the elastic medium surrounding the main calculation cell. Anisotropy is taken into account by introducing an explicit angular dependence for the parameters of the elastic field created by the dislocation: magnitude of Burgers vector and Poisson’s ratio. Simulation is carried out for a split dislocation with Burgers vector along [100]. The convergence of the iterative algorithm is shown and the influence of the computational cell size on the results is considered. Calculated results are: atomic structure of dislocation in bcc iron, angular dependence of the parameters describing the elastic dislocation field at large distances from the dislocation line, and the strain tensor components in the entire simulation area.

Highlights

Segregation of certain elements in the vicinity of the dislocation lines alters the structure of the defect core that affects the ductility of the material
We simulate the structure of the core of the edge dislocation, and its surroundings using the modified method of molecular statics, taking into account the anisotropy of the elastic field at the boundary of the computational cell
The developed model makes it possible to match the displacements of atoms at the boundary of the main computational cell with the displacements of atoms located in an elastic medium, and calculate the components of the strain tensor in the entire computational domain

Summary

Introduction

Segregation of certain elements in the vicinity of the dislocation lines alters the structure of the defect core that affects the ductility of the material. A necessary prerequisite for this is information on the atomic structure of the dislocation core. In this regard, we simulate the structure of the core of the edge dislocation, and its surroundings using the modified method of molecular statics, taking into account the anisotropy of the elastic field at the boundary of the computational cell. The developed model makes it possible to match the displacements of atoms at the boundary of the main computational cell with the displacements of atoms located in an elastic medium, and calculate the components of the strain tensor in the entire computational domain. The obtained strains are supposed to be used in the future for modeling the kinetics of the redistribution of impurity atoms in the dislocation field

Model description

Results and discussion

Conclusion