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Vacancy-like defects in NiAl in the composition range 47 at.-% < CNi < 53 at.-% are investigated by means of positron lifetime spectroscopy and Doppler-broadening measurements. The observed lifetimes in the annealed samples confirm that defects are quenched-in during the production of the samples. Isochronal annealing of samples quenched at 1600'C and after proton irradiation show that the induced defects are quite different.

Vacancy-like defects in CoAl in the composition range 48.5 at.-% <Cco, < 53 at.-% are investigated by means of positron lifetime spectroscopy and Doppler-broadening measurements. The observed lifetimes in the annealed samples confirm that defects are quenched-in during the production of the samples. The values of the positron lifetime and the S-parameter decrease with increasing Co concentration. After quenching from 1400°C or 1600°C an increase in the positron parameters isobserved. Long-time annealing of the Co-rich sample shows a dramatic decrease of the positron lifetime to the expected bulk lifetime.