Structure of complex oxide nanoparticles in a Fe-14Cr-2W-0.3Ti-0.3Y2O3 ODS RAF steel

One of the most crucial steps in the development of oxide dispersion strengthened (ODS) reduced activation ferritic (RAF) steels is the engineering of their microstructure, which includes control of the type and size of oxide nanoparticles. In this work, the composition and crystal structure of oxide particles grown in the Fe–14Cr–2W–0.3Ti–0.3Y2O3 ODS RAF steel were characterized using advanced spectroscopic and microscopic techniques. The electron energy loss spectroscopic mapping has shown presence of numerous fine Y–Ti–O oxides but also larger Cr–Ti–O and Cr–N particles among those extracted from the bulk samples. In addition, atom probe tomography of the as-compacted ODS RAF samples revealed a uniform spatial distribution of fine oxides containing mainly Y, Ti, and O. The orthorhombic YTiO3, having distorted perovskite structure, was identified in all analyzed oxides using HR-STEM and diffraction pattern analysis.