Bubble-to-void transition promoted by oxide nanoparticles in ODS-EUROFER steel ion implanted to high He content

The paper deals with a detailed study of He-filled cavity ensemble development in ODS-EUROFER steel implanted with 10 keV helium ions to a high peak concentration of 8.5 x 10(3) appm both with and without simultaneous irradiation with 4 MeV gold ions, which allowed us to strongly vary the ratios of dpa/He introduction. The subsequent transmission electron microscopy examination reveals excellent radiation stability of He-implanted sample in the single-beam implantation mode. In contrast, after the simultaneous dual-beam irradiation a bubble-to-void transition was observed for bubbles that were associated with yttria nanoparticles. The relative importance of different He bubble families observed in the He-implanted samples for the swelling accumulation is quantitatively assessed, emphasizing the potential risks of abrupt swelling acceleration in the case of bubble-to-void transition launched by nanoparticles. A model of bubble-to-void transition for gas bubbles associated with spherical second-phase particles is developed and used to rationalize experimental observations. (C) 2020 EURATOM. Published by Elsevier B.V. All rights reserved.

Automated summary

The study showed that different injection modes in ODS-EUROFER steel have varying effects on bubble formation and radiation stability, with nanoparticles potentially leading to a bubble-to-void transition. Quantitative assessment of bubble families can help prevent swelling acceleration.