Short communication: Complete dissolution of MX-phase nanoprecipitates in fusion steels during irradiation by heavy-ions

New RAFM steels, with intragranular VN precipitates for enhanced creep strength, were irradiated with 2MeV Fe+ ions at 600 °C to explore MX-type precipitate response to extreme end-of-life conditions in breeder blanket components. Utilizing TEM, Analytical-STEM, and APT, the steels were characterized in the unirradiated and irradiated states. Unirradiated grains contained needle-like VN precipitates (∼1 × 1022/m2). However, throughout the 40–100 dpa irradiation damage layer, VN precipitates were completely annihilated. APT confirmed no fine-scale VN clustering, indicating re-solution with the matrix, suggesting instability. Further investigations via reactor irradiations are crucial to assess this instability under breeder blanket conditions.