Development of nano-oxide particles dispersed alumina scale formed on Zr-added FeCrAl ODS ferritic alloys. (December 2020)

• Record Type: Journal Article
• Authors: Yu, Hao; Kondo, Sosuke; Kasada, Ryuta; Oono, Naoko; Hayashi, Shigenari; Ukai, Shigeharu
• Is Part Of: Nuclear materials and energy. Volume 25(2020)
• Publication Date: 2020-12
• Subjects: FeCrAl ferrite -- ODS -- Oxidation -- Alumina; Nuclear energy -- Periodicals; Nuclear fuels -- Periodicals; Nuclear reactors -- Materials -- Periodicals; Radioactive substances -- Periodicals; 621.4833
• DOI: 10.1016/j.nme.2020.100798
• Languages: English
• ISSNs: 2352-1791

Abstract

Highlights: Oxidation of FeCrAl ODS alloys with different excessive oxygen additions was investigated. Dense Y-Zr oxide particles dispersed alumina scale was developed at 900 °C in air. Unique tadpole-like shape of the Y-Zr oxide particles in alumina was observed. Abstract: In order to develop a robust alumina scale dispersed with nano-oxide particles for FeCrAl oxide dispersion strengthened (ODS) ferritic alloys, the oxidation behavior of FeCrAl ODS ferritic alloys with zirconium and excessive oxygen (Ex. O) additions was investigated at 900 °C in air. Zirconia incorporation into alumina scale was not observed in the Ex. O-added FeCrAl ODS alloys at 900 °C, instead of this, a distribution with dense Y-Zr oxide particles inside the alumina scale was found, which is expected to enhance the stability of the alumina scale during service at elevated temperatures in nuclear applications. Preexisting large Zr-enriched precipitates formed during the alloy fabrication process are incorporated into the alumina scales during oxidation, which would increase the oxidation rate via providing a short-circuit paths for oxygen inward diffusion by themselves and associated porosity. In addition to a traditional spherical shape, a unique tadpole-like shape of the fine Y-Zr oxide particles in alumina was also observed, which is considered to be related to those incorporated coarse Zr-Y oxide inclusions in alumina scale.