INTERATOMIC POTENTIALS FOR B2 NIAL AND MARTENSITIC PHASES

Interatomic potentials of the embedded atom type were developed for the Ni-Al system by empirical fitting to the properties of B2 NiAl and Ni5Al3. Consideration was also given to the properties of Ll(2) Ni3Al as well as the martensitic Ll(0) phase. The B2 phase is predicted as the stable phase for the equi-atomic composition. The potentials also predict the stability of the 3R martensitic structure with respect to the B2 phase for 62.5% Ni alloys. The globally stable phase for this composition is the Ni5Al3 structure. The predicted lattice parameters and tetragonality ratios for Ni5Al3 and 3R martensite are very close to experimental values. The structure and energy of various defects was calculated using the new potentials and the results compared with those given by other potentials in the literature.