Defect structures and ternary lattice site preference of the B2 phase in the Al–Ni–Ru system

Abstract The energies for stoichiometric and defected binary and ternary B2 phases in the Al–Ni–Ru ternary system were calculated from first-principles. The dominant compositions-conserving constitutional defect structures for NiAl and RuAl have been determined as (Al, Ni)(Ni, Va) and (Ru, Al, Va)(Al), respectively. It was observed that Ru prefers the Ni-sublattice in NiAl, while Ni has a very strong preference for the Ru-sublattice in RuAl. Furthermore, the results indicate that a miscibility gap is likely to be stable at low temperatures in the NiAl–RuAl pseudobinary system.