Ab initio calculations of the stability and structural defects of the B2 CuxFe1−x Al phases

The stability of the B2 CuxFe1−x Al phases and the energy of defect formation are studied using ab initio band calculations. For B2 CuxFe1−x Al alloys, vacancies in the 3d-metal sublattice and configurations with the minimum number of Fe-Cu bonds in the first coordination shell (including Fe antisite defects, which have a high local magnetic moment) are most stable. Complicated defect complexes with vacancies and displaced atoms, which are close to the atomic configurations of vacancy-ordered AlCu phases, can exist near the composition Cu0.875Fe0.125Al.