Study of defects introduced by 2 and 9 MeV electron irradiation in B2 type Fe-Al alloy

It is well known that B2 type Fe-Al intermetallic compound alloy possibly includes more than two types of vacancies basically, that is Fe-vacancy and Al-vacancy. Although MeV ordered electron irradiation produces vacancies and interstitials, the threshold energy of displacement for each elemental atom in intermetallic alloys is not necessarily same. In this study, we performed positron annihilation lifetime and Doppler broadening measurements for different energy of electron irradiated B2 ordered Fe50%Al alloy. Different values of positron annihilation lifetime for 2 and 9 MeV electron irradiation were measured. Also, the Doppler broadening S and W parameters showed different changing trend for different energy of electron irradiation. These results suggest that selective atomic displacement takes place in Fe-Al ordered alloy by electron irradiation with different energies.