The energies of stoichiometric and defected binary and ternary B2 phases in the this ternary system were calculated from first-principles. The dominant composition-conserving constitutional defect structures for NiAl and RuAl were determined to be (Al,Ni)(Ni,Va) and (Ru,Al,Va)(Al), respectively. It was observed that Ru preferred the Ni sub-lattice in NiAl, whereas Ni had a very strong preference for the Ru sub-lattice in RuAl. The results indicated that a miscibility gap was likely to be stable at low temperatures in the NiAl–RuAl pseudobinary system.

Defect Structures and Ternary Lattice Site Preference of the B2 Phase in the Al–Ni–Ru System. S.Prins, R.Arroyave, Z.K.Liu: Acta Materialia, 2007, 55[14], 4781-7