On the Stability of Nanostructured 18-Chromium ODS Steels under High Dose Ion-Irradiation

Ferritic-Martensitic Oxide Dispersion Strengthened (ODS) steels are promising candidates for fuel cladding of high burn-up fast neutron reactors. To meet requirements, the stability of reinforcing nano-oxides has to be settled in the irradiation and temperature service conditions. In this work, ion irradiations are performed on 18-Chromium ODS steels and the induced microstructural modifications are investigated by the Transmission Electron Microscopy and Atom Probe Tomography complementary techniques. In-situ irradiations (CSNSM-JANNuS Orsay) of Fe18Cr1W0.4Ti+O.6Y2O3 showed that Y-Ti-O nanoclusters are apparently stable up to 45 dpa at 500 degree C. However, at 235 dpa (SRMP-JANNuS Saclay), radiation-induced modifications of sizes and compositions were suspected.Furthermore, inert gaz irradiations (IVEMArgonne) performed on a Fe18Cr1W0.8Ti+0.3MgO model ODS alloy showed that the coherency of oxide/matrix interfaces plays a key role on the nucleation of Kr-stabilized cavities at room temperature.