Core/shell structures of oxygen-rich nanofeatures in oxide-dispersion strengthened Fe-Cr alloys

With the significant improvement in high temperature creep properties and resistance to radiation damage by addition of nanoscale oxide features, oxide-dispersion strengthened (ODS) ferritic/martensitic alloys are potential candidates for structural applications in nuclear fusion reactors. The structure of the oxygen-rich nanofeatures was analyzed by atom-probe tomography in three ODS alloys: MA957, ODS Fe-12 wt %Cr, and ODS Eurofer-97. Although field evaporation and reconstruction of the precipitates suffer from artefacts, a core/shell structure is found even for very small precipitates. Precipitate cores are Y rich while shell regions are enriched in Ti, Cr, or V depending on alloy composition.