Constitutional and thermal point defects in B2 NiAl
2000 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 61, no 9, 6003-6018 p.Article in journal (Refereed) Published
The formation energies of point defects and the interaction energies of various defect pairs in NiAl are calculated from first principles within an order N, locally self-consistent Green's-function method in conjunction with multipole electrostatic corrections to the atomic sphere approximation. The theory correctly reproduces the ground state for the off-stoichiometric NiAl alloys. The constitutional defects (antisite Ni atoms and Ni vacancies in Ni-rich and Al-rich NiAl, respectively) are shown to form ordered structures in the ground state, in which they tend to avoid each other at the shortest distance on their sublattice. The dominant thermal defects in Ni-rich and stoichiometric NiAl are calculated to be triple defects. In Al-rich alloys another type of thermal defect dominates, where two Ni vacancies are replaced by one antisite Al atom. As a result, the vacancy concentration decreases with temperature in this region. The effective defect formation enthalpies for different concentration regions of NiAl are also obtained.
Place, publisher, year, edition, pages
2000. Vol. 61, no 9, 6003-6018 p.
transition-metal aluminides, vacancy-formation energy, electronic-structure, intermetallic compounds, mechanical-properties, atomistic simulation, physical-properties, optical-properties, charge-density, phase-diagram
Physical Sciences Metallurgy and Metallic Materials Physical Chemistry
IdentifiersURN: urn:nbn:se:kth:diva-19601DOI: 10.1103/PhysRevB.61.6003ISI: 000085707100042OAI: oai:DiVA.org:kth-19601DiVA: diva2:338293
QC 20100525 QC 20120208 NR 201408042010-08-102010-08-102012-02-13Bibliographically approved