This thesis aims to optimize the performance of future nuclear steels. Martensitic steels are particularly studied for the components of sodium-cooled fast reactor cores, as they exhibit lower swelling under irradiation compared to austenitic grades. To improve their creep properties, these steels are sometimes reinforced with a fine dispersion of stable nanometric oxides (Oxides Dispersed Strengthened). However, conventional martensitic ODS steels, with chromium content limited to 9-11 %Cr, often suffer from low toughness at room temperature.
Recent research indicates that the toughness of ODS steels could be significantly enhanced with very low carbon content. This thesis proposes an original approach that combines the exceptional toughness and corrosion resistance of Maraging steels with an ODS-type precipitation. Indeed, the Maraging stainless steels are rich in chromium (10-15 %) and nickel (4-9 %), with carbon content below 0.02 % by weight. After austenitization and quenching, these steels exhibit a martensitic structure, providing an outstanding balance between yield strength and toughness.
To evaluate the performance of these disruptive grades, compositions of interest will be selected, developed, and characterized at CEA with collaboration of academic partner teams.

JOB PROFIL: The applicant must be master-2 graduated with training in materials science and ideally metallurgy. The proposed subject is mainly experimental. A basic knowledge of electronic microscopy and/or XRay diffraction is required for this position. At the end of the PhD the applicant will be highly skilled in steel metallurgy and will have operated a large number of microstructural characterizations advanced tools (SEM, TEM, SAXS XRD, DSC). Naturally, he/she can pretend to a metallurgy researcher position in a large range of industries.