Irradiation-Induced Defects and Cu Precipitates in Ternary Fe-Based Model Alloys for Nuclear Reactor Pressure Vessel Steels Studied by Positron Annihilation and 3D Atom Probe

摘要

Positron annihilation and three dimensional (3D) atom probe techniques are employed to study irradiation-induced defects and ultrafine Cu precipitates in model alloys for nuclear reactor pressure vessel (RPV) steels, Fe-0.3Cu-0.7Ni and Fe-0.3Cu-1.5Mn after irradiation by 3MeV electrons. The coincidence Doppler broadening (CDB) and positron lifetime clearly showed the vacancy-multi Cu atom complexes for all the alloys after irradiation. Positron annihilation revealed that the vacancies anneal out but Cu atoms aggregate to the ultrafine Cu precipitates by post-irradiation annealing at 400°C. The 3D atom probe also shows the Cu precipitate, but no enrichment of Ni or Mn atoms therein, which is consistent with the results of positron annihilation.