Specimens of the intermetallic compound Ni3Al were irradiated by 2MeV electrons at room temperature or quenched from 900 to about 1300C and subsequently annealed isochronally. The behaviour of the vacancies was studied using the positron lifetime. The vacancies annealed out around 215C. The formation energy of a vacancy was determined to be EvF = 1.6eV. The activation energy for the motion of the vacancy was estimated to be EvM = 1.2eV. The annealing of the vacancies was found to be a second-order reaction.

Study of Vacancies in the Intermetallic Compound Ni3Al by Positron Annihilation. Wang, T.M., Shimotomai, M., Doyama, M.: Journal of Physics F, 1984, 14[1], 37-45