Elastic dipole tensors and relaxation volumes of point defects in concentrated random magnetic Fe-Cr alloys

Elastic dipole tensors and relaxation volumes of point defects in concentrated random magnetic Fe-Cr alloys

Elastic dipole tensors and relaxation volumes of point defects in concentrated random magnetic Fe-Cr alloys 150 150 amit lakhani
UKAEA-CCFE-PR(20)79

Elastic dipole tensors and relaxation volumes of point defects in concentrated random magnetic Fe-Cr alloys

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 study

suggests that magnetism is a significant factor influencing elastic fields of defects in Fe-Cr alloys.  

Collection:
Journals
Journal:
Physical Review B
Publisher:
APS (American Physical Society)
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