The structural changes of Y2O3 in ferritic ODS alloys during milling

Oxide dispersion strengthened (ODS) ferritic steels are usually fabricated via mechanical alloying and subsequent consolidation via hot extrusion or hot isostatic pressing. During the individual process steps, a complex evolution of the nanoparticle structure is taking place. Powders with different Y2O3 contents were milled and examined by means of X-ray diffraction (XRD) and atom probe tomography (APT). It has been observed that the Y2O3 is fragmented and becomes partially amorphous upon milling due to the grain refinement of Y2O3 during the milling process. There was no compelling evidence for Y2O3 dissociation and dissolution into the steel matrix.