Defect recovery in electron irradiated Ni(sub 2)Si intermetallic compounds

摘要

Specimens of Ni(sub 2)Si intermetallic compound are studied by means of positron annihilation spectroscopy (P.A.S.) after electron irradiation at 20 K. Isochronal spectra of the positron average lifetime and of the Doppler broadening parameter are followed from low temperature to 750 K. The results for both methods are in fair agreement. In irradiated samples interstitials migrate and recombine with immobile vacancies at a temperature as low as 77 K. From 325 K vacancies became mobile and lead to the formation of tridimensional mixed clusters. At about 400 K, the less stable clusters evaporate. The recovery is still incomplete at 700 K. The positron lifetime variation as a function of measuring temperature made it possible to characterize the dimensional nature of the clusters formed during the annealing. Present results are compared with previous ones obtained in pure nickel and Ni-Si (0.8 at%) solid solutions. (authors). 3 figs., 15 refs. (Atomindex citation 26:052294)