Empirical many-body central-force potentials of Finnis-Sinclair type were constructed for the B2 structure by matching various properties of the alloy and by reproducing the asymmetrical behavior of constitutional point defects in off-stoichiometric material. These potentials ensured the structural and mechanical stability of the B2 lattice, and reproduced the equilibrium properties of Ni3Al quite closely. By using these potentials, grain boundaries in NiAl were studied via computer simulation. It was found that, in stoichiometric samples, boundaries with an excess of Al had appreciably lower cohesive strengths than did stoichiometric boundaries or boundaries with an excess of Ni. Boundaries with an excess of Al exhibited the largest expansions, and large holes usually occurred in the boundary regions. Boundaries with a stoichiometric composition, or with an excess of Ni, had more compact structures.

M.Yan, V.Vitek, S.P.Chen: Acta Materialia, 1996, 44[11], 4351-65