Theoretical and experimental aspects of positron annihilation studies of precipitate-relevant phenomena in Fe-Cu model alloys of reactor pressure vessel steels were considered. Although the positrons were generally thought to be insensitive to the impurities in solids, it was demonstrated that the positrons could be confined as a quantum-dot state within the nano Cu or Cu-rich precipitates in Fe-Cu model alloys. A positron probe was successfully used to clarify that the nano Cu precipitate had a body-centred cubic structure that was coherent with the Fe matrix. The results clearly showed that the quantum-dot state positrons exclusively detected the microscopic and electronic structures of the precipitates.

Irradiation-Induced Vacancy and Cu Aggregations in Fe-Cu Model Alloys of Reactor Pressure Vessel Steels - State-of-the-Art Positron Annihilation Spectroscopy. M.Hasegawa, Z.Tang, Y.Nagai, T.Chiba, E.Kuramoto, M.Takenaka: Philosophical Magazine, 2005, 85[4-7], 467-78