Point defects in body-centred cubic Fe, Cr and concentrated random magnetic Fe-Cr are investigated
using density functional theory and theory of elasticity. The volume of a substitutional
Cr atom in ferromagnetic bcc Fe is approximately 18% larger than the volume of a host Fe atom,
whereas the volume of a substitutional Fe atom in antiferromagnetic bcc Cr is 5% smaller than the
volume of a host Cr atom. Elastic dipole P and relaxation volume tensors Ω of vacancies and
self-interstitial atom (SIA) defects exhibit large fluctuations, with vacancies having negative and
SIA large positive relaxation volumes. Dipole tensors of vacancies are nearly isotropic across the entire alloy
composition range, with diagonal elements Pii decreasing as function of Cr content.
Fe-Fe and Fe-Cr SIA dumbbells are more anisotropic than Cr-Cr dumbbells. Fluctuations of elastic
dipole tensors of SIA defects are primarily associated with the variable orientation of the defects.
Statistical properties of tensors P and Ω are analysed using their principal invariants, suggesting
that point defects differ significantly in alloys containing below and above 10 at. % Cr. The relaxation
volume of a vacancy depends sensitively on whether it occupies a Fe or a Cr lattice site. A
correlation between elastic relaxation volumes and magnetic moments of defects found in this studysuggests that magnetism is a significant factor influencing elastic fields of defects in Fe-Cr alloys.