Screw dislocation interaction with magnetic solutes in bcc iron in the paramagnetic state
Title: Screw dislocation interaction with magnetic solutes in bcc iron in the paramagnetic state
SNIC Project: LiU-compute-2020-23
Project Type: LiU Compute
Principal Investigator: Luis Alberto Casillas Trujillo <lkasillas@gmail.com>
Affiliation: Linköpings universitet
Duration: 2020-07-07 – 2021-08-01
Classification: 10304
Keywords:

Abstract

The interaction of solutes with screw dislocation in bcc materials have a strong impact on the structure and mobility of dislocation cores, that translates in macroscopic effects such as hardening and softening effects. The magnetic and atomic volume landscape in the paramagnetic state of iron greatly differs from that in the ferromagnetic state. Such difference can have an important impact in the formation energies of substitutional impurities, in particular magnetic solutes. In this work, we investigate the formation energies as a function of position with respect to the dislocation core of Cr, Co and Mn solutes in paramagnetic bcc iron. To address paramagnetism, we use the non-collinear disordered local moment approximation (DLM) and perform structural relaxations with density functional theory (DFT). The inherent DFT cell size restriction carries a self-interaction of the solute due to periodicity. To address this effect, we investigate the repulsion energy of the solutes with cells of 2 and 3 Burgers vectors thickness. The structural relaxations will reveal if the presence of solutes alter the dislocation core structure from the easy to the hard core configuration, which carries a change in the preference on the slip planes and thus an increased dislocation mobility.