Positron affinity for precipitates in reactor pressure vessel steels

Effects of solute atoms on evolution of vacancy defects in electron-irradiated Fe–Cr-based alloys

“…Cr The positrons are not sensitive to the nitride (carbide) because its positron affinity is lower than that of the Fe matrix [19].…”

Positron annihilation study of effects of Ti and plastic deformation on defect accumulation and annealing in electron-irradiated austenitic steels and alloys

“…These particles were able not only to block the capture of positrons by dislocations and pin the dislocations, but also could serve as positron trapping centers themselves. Precipitates could capture positrons either as a result of preferred affinity [28,29] or owing to the incoherence of particles by misfit dislocations [30]. According to calculations [29], most of carbides have not a preferred affinity as compared with host materials.…”

“…Precipitates could capture positrons either as a result of preferred affinity [28,29] or owing to the incoherence of particles by misfit dislocations [30]. According to calculations [29], most of carbides have not a preferred affinity as compared with host materials. Therefore, positrons can be captured only by misfit dislocations, which are connected with carbide particles.…”

Evaluation of some basic positron-related characteristics of SiC

“…12 The application of improved LMTO-ASA calculations to different polytypes of SiC allows a more reliable treatment, compared to the atomic superposition method, of the following: ͑i͒ bulk positron lifetimes; ͑ii͒ positron lifetimes in monovacancies and divacancies and the influence of an impurity atom in the vicinity of these defects; and ͑iii͒ positron trapping in clusters of Si or Ge atoms, which might be formed by ion implantation. This last calculation was prompted by the fact that the bulk positron lifetimes given in the literature 13 for Si ͑218 ps͒ and Ge ͑230 ps͒ are both close to the experimental lifetime ͑235Ϯ3͒ ps found after ion implantation.…”