Journal of Physics: Condensed Matter, 18, 8859-8876, (2006)
C. D. Latham (a,b), S. Öberg (a), P. R. Briddon (c) and F. Louchet (d)
(a) Institutionen för matematik, Luleå Tekniska Universitet, SE-97187 Luleå, Sweden
(b) Sähkötekniikan osasto, Lappeenrannan teknillinen yliopisto, PL 20, FIN-53851 Lappeenranta, Finland
(c) Physics Centre, School of Natural Science, University of Newcastle upon Tyne, Newcastle NE1 7RU, UK
(d) LGGE, 54 rue Molière, BP 96-Domaine Universitaire, F-38402 Saint Martin d'Hères, France
(Received 17 February 2006; in final form 19 July 2006; published 15 September 2006)
The structures and energies of point defects and point defect complexes in B2 iron aluminium FeAl are calculated using a local density functional theory based method with large supercells. Particular emphasis is given to pseudopotential quality, choice of chemical potentials used to calculate defect formation energies, and how these are affected by magnetism. Both purely native defects and ones containing boron atoms are considered. It is found that the relative stabilities of isolated point defects versus defect complexes depends on whether the material contains excess iron or aluminium. The situation in material containing boron is further complicated by the existence iron borides in more than one form. We propose that the interaction between point defects, dislocations, and antiphase boundaries, where the local atomic environment has some similarities with antisite defects, also depends on the alloy composition. It is likely that these interactions are part of the underlying mechanism responsible for the unusual mechanical properties of iron aluminides.
DOI: 10.1088/0953-8984/18/39/016
PACS: 61.72.Bb, 61.72.Ji, 71.15.Nc, 71.20.Lp
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