Nanoscale characterisation of ODS-Eurofer 97 steel: An atom-probe tomography study

Laser-pulsed atom-probe tomography has been used to study the nanoscale features present in an ODS-Eurofer 97 alloy. A core/shell structure was found for particles 5-10 nm in diameter. The particle cores were primarily Y and O, enriched with Mn and Si resulting in a metal (Y, Mn and Si) to oxygen ratio of M:O ∼2:3. The ∼2 nm thick outer-shell region of the particles exhibited partitioning of V, Cr, Ta, C and N together with the core elements in many cases. Detailed compositional measurements have also been made on the smallest of the yttria-based oxide clusters down to 2 nm in diameter. The 2 nm clusters were found to have a non-stoichiometric oxide composition, enriched in oxygen compared to Y2O3, and evidence for the existence of a shell around these smaller particles was found.