Atomistic simulations of dislocations in iron-chromium alloys

Dislocations in bcc metals exhibit large differences in their mobilities. While pure screw dislocations experience high lattice resistance due to their non-planar cores, all non-screw dislocations are expected to glide easily at low applied stresses. However, dislocation properties can change significantly in alloys due to different chemical bonding and size mismatch of the constituting elements.

In this work, we investigate properties of dislocations in the Fe-Cr system that is both technologically important and scientifically challenging since many structural, mechanical and thermodynamic properties of this system are governed by magnetic interactions. To obtain a comprehensive picture, we employ a range of atomistic methods including first-principles calculations, tight binding and related magnetic bond-order potentials, as well as classical interatomic potentials. We will present an analysis of both static (structural, magnetic) and dynamic (behavior under applied stress) properties of dislocations for various Fe-Cr compositions and discuss the implications on the plastic behavior.