Samples with differing defect concentrations were studied by using positron annihilation lifetime and Mössbauer spectroscopic methods. The predominant component of 178 to 187ps, which was deduced from positron lifetime spectral analyses, corresponded to a high density of vacancies. In samples where high concentrations of vacancies or dislocations and vacancy clusters were found simultaneously, a second component with a lifetime of 335ps appeared. The Mössbauer results showed that, in this alloy which was above the Fe3Al stoichiometric concentration, the vacancies preferred to occupy the sub-lattice in the D03 superstructure which was reserved for both Fe and Al atoms. However, this conclusion could not be verified, by a comparison of theoretical and experimental values of the positron lifetimes, because the theoretically predicted positron lifetimes for all 3 types of vacancy were almost the same.

Y.Jirásková, O.Schneeweiss, M.Sob, I.Novotný, I.Procházka, F.Becvár, B.Sedlák, F.Sebesta, M.J.Puska: Journal de Physique III, 1995, 5[C1], 157-61