Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

Physical and mechanical properties of Fe-Al alloys are strongly influenced by atomic ordering and point defects. In the present work positron lifetime (LT) measurement combined with slow positron implantation spectroscopy (SPIS) were employed for investigation of quenched-in vacancies in Fe-Al alloys with Al content ranging from 18 to 49 at.%. Interpretation of positron annihilation data was performed using ab-inito theoretical calculations of positron parameters. Quenched-in defects were identified as Fe-vacancies.
It was found that the lifetime of positrons trapped at quenched-in defects increases with increasing Al content due to increasing number of Al atoms surrounding vacancies. The concentration of quenched-in vacancies strongly increases with increasing Al content from ~10e-5 in Fe82Al18 (i.e. the alloy with the lowest Al content studied) up to ~ 10e-1 in Fe51Al49 (i.e. the alloy with the highest Al content studied in this work).