Multiscale modeling of crowdion and vacancy defects in body-centered-cubic transition metals

Journal Article · Wed Aug 01 04:00:00 EDT 2007 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.76.054107· OSTI ID:21055095

Derlet, P M ^[1]; Nguyen-Manh, D ^[2]; Dudarev, S L ^[2]

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1. Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland)
2. EURATOM/UKAEA Fusion Association, Culham Science Centre, Oxfordshire OX14 3DB (United Kingdom)

We investigate the structure and mobility of single self-interstitial atom and vacancy defects in body-centered-cubic transition metals forming groups 5B (vanadium, niobium, and tantalum) and 6B (chromium, molybdenum, and tungsten) of the Periodic Table. Density-functional calculations show that in all these metals the axially symmetric <111> self-interstitial atom configuration has the lowest formation energy. In chromium, the difference between the energies of the <111> and the <110> self-interstitial configurations is very small, making the two structures almost degenerate. Local densities of states for the atoms forming the core of crowdion configurations exhibit systematic widening of the ''local'' d band and an upward shift of the antibonding peak. Using the information provided by electronic structure calculations, we derive a family of Finnis-Sinclair-type interatomic potentials for vanadium, niobium, tantalum, molybdenum, and tungsten. Using these potentials, we investigate the thermally activated migration of self-interstitial atom defects in tungsten. We rationalize the results of simulations using analytical solutions of the multistring Frenkel-Kontorova model describing nonlinear elastic interactions between a defect and phonon excitations. We find that the discreteness of the crystal lattice plays a dominant part in the picture of mobility of defects. We are also able to explain the origin of the non-Arrhenius diffusion of crowdions and to show that at elevated temperatures the diffusion coefficient varies linearly as a function of absolute temperature.

• OSTI ID: 21055095
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 5 Vol. 76; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BCC LATTICES
CHROMIUM
CROWDIONS
DEFECTS
DENSITY FUNCTIONAL METHOD
DIFFUSION
ELECTRONIC STRUCTURE
EXCITATION
FORMATION HEAT
INTERSTITIALS
MOLYBDENUM
NIOBIUM
TANTALUM
TUNGSTEN
VACANCIES
VANADIUM