Quenched-in vacancies in Fe₃Al based alloys: a positron annihilation study

In the present contribution, high-resolution positron lifetime spectroscopy and slow positron implantation spectroscopy are used to characterize defects in Fe_75.99Al_24.01 and Fe_71.98Al_28.02 alloys. In order to facilitate defect identification, we also perform a theoretical study of basic vacancy-like defects in three phases of the Fe₃Al system: ordered (D0₃), shortrange ordered (B2) and disordered (A2). Positron characteristics, i.e. positron lifetime and positron binding energy to defects are calculated from the first principles for various defect configurations. The results are discussed in the context of experimental data obtained here and available in literature.