Small-angle neutron scattering (SANS) characterization of 13.5 Cr oxide dispersion strengthened ferritic steel for fusion applications

• Published in: Nuclear materials and energy 2020-08, Vol.24, p.100778, Article 100778
• Main Authors: Coppola, R., Klimenkov, M., Lindau, R., Mangiapia, G.
• Format: Article
• Language: English
• Subjects: Electron microscopy; Ferritic/martensitic steels; ODS steels; Small-angle neutron scattering
• ISSN: 2352-1791; 2352-1791
• DOI: 10.1016/j.nme.2020.100778

•Innovative ferritic ODS steel laboratory heats have been investigated by SANS.•SANS data analysis reveals Y-Ti-O nano-clusters invisible by TEM and provides information on their Ti content.•SANS data analysis provides quantitative base for modeling micro-structural evolution. Small-angle neutron scattering (SANS) has been utilized for micro-structural investigation on laboratory heats of oxide dispersion strengthened (ODS) 13.5 Cr wt % ferritic steel, with 0.3 wt% Y2O3 and with variable Ti and W contents. The results show that increasing the Ti content from 0.2 to 0.4 wt% a distribution of nano-clusters develops, tentatively identified as Y2Ti2O7, with average radii as small as 6.5 Å and volume fractions increasing from 0.021 to 0.032. The measured SANS cross-sections show also the growth of much larger defects, possibly Cr oxides. Furthermore, the ratio of magnetic to nuclear SANS components shows that the defect composition varies both with their size and with the Ti and the W content. These results are in qualitative agreement with transmission electron microscopy (TEM) observations, showing a striking influence of Ti addition on particle size refinement. However, while TEM is limited in statistics and minimum observable size of the Ti-rich nano-clusters, the defect distributions obtained by these SANS measurements provide complementary information useful for morphological characterization of the micro-structure in the investigated material.