Change of the defect structure in FeAl alloy as a result of its aging at ambient temperature

Positron annihilation lifetime spectroscopy (PALS) was used to study the defect structure of stoichiometric FeAl samples after their slow cooling or quenching from the temperatures of 1000 and 540 centigrade. The high value of positron lifetime in the quenched-in defects suggests that they are mainly of di-vacancy type. After long storage at ambient temperature, the concentration of defects in the samples strongly decreases and mono-vacancies predominate. Annealing at 540 centigrade generates an additional amount of defects may be ascribed to the formation of FeAl2 phase in the FeAl matrix.