Inversion of Dislocation-Impurity Interactions in $\alpha$-Fe under Magnetic State Changes

TL;DR

This study uses ab initio methods to analyze how magnetic state changes in $ ext{Fe}$ affect dislocation-impurity interactions, revealing significant magnetic influence and state-dependent interaction profiles for various 3d elements.

Contribution

It introduces a detailed ab initio analysis of dislocation-impurity interactions in $ ext{Fe}$ considering magnetic state changes, highlighting the magnetic effects over size misfit effects.

Findings

Magnetic effects dominate impurity interaction energies.

Dislocation-impurity interactions depend on magnetic state and temperature.

Cu interaction switches from attractive to repulsive with magnetic state change.

Abstract

In this work, we investigate the dislocation-impurity interaction energies and their profiles for various \textit{3d} elements \textemdash V, Cr, Mn, Cu, Ni, and Co \textemdash in and around $1/2\langle111\rangle$ screw dislocations in $\alpha$-Fe using \textit{ab initio} methods. We consider the ferromagnetic and paramagnetic states, with the latter being modeled through both the disordered local moment model and a spin-wave approach. Our findings reveal that (1) magnetic effects are large compared to size misfit effects of substitutional impurities, and (2) dislocation-impurity interactions are dependent on the magnetic state of the matrix and thermal lattice expansion. In particular, Cu changes from core-attractive in the ferromagnetic state to repulsive in the paramagnetic state.