Positron annihilation in structural vacancies in B2 Al-rich NiAl alloys was studied theoretically. For this purpose the atomic superposition method, combined with molecular dynamics employed for relaxations of random vacancy configurations, were used. It was found that the defect lifetime decreased with increasing Ni vacancy concentration. Calculated positron lifetimes were considered in terms of the so-called vacancy-superstructure effect and compared with experimental positron lifetime data available.

Positron Annihilation in Structural Vacancies in Al-Rich NiAl Alloys. A.L.Morales, L.A.Leon, N.Raigoza, C.A.Duque, J.Kuriplach, M.Hou: Physica Status Solidi C, 2007, 4[10], 3534-7