Atomic Defects and Electronic Structure of B2 FeAl, CoAl and NiAl

摘要

The effective formation energies for vacancies and antistructure atoms on both sub-lattices of the B2 structure are calculated for the triad FeAl, CoAl and NiAl by a combination of statistical mechanics with the ab-initio density functional electron theory. The basic assumption is that the defects are noninteracting which can be valid only for small defect concentrations. It is shown that for this approximation the structural defects in Al-rich NiAl and CoAl are definitely vacancies on the transition-metal sublattice and not Al antistructure atoms. The binding energies for various defect pairs in FeAl and NiAl are also calculated, and remarks on the interpretation of the defect energetics in terms of electronic bonding properties are made.