Microstructure morphology and tensile properties of 9Cr-ODS steels added different Y2O3 contents

Abstract

Oxide dispersion strengthened (ODS) steels are considered to be the promising structural material candidates for Generation IV fission reactors, fusion reactor applications, new accident-tolerant fuel (ATF) cladding materials. In this study, different contents of Y2O3 were added into 9Cr-ODS steels to realize different Y/Ti atomic ratios. The microstructure of samples, kinds, number densities and size distribution characteristic of nano-scale oxide-precipitates formed in the 9Cr-ODS steel samples were investigated by synchrotron radiation SAXS, XAFS spectrum and TEM, explained the effect of Y2O3 contents on microstructures of 9Cr-ODS steel samples. The tensile properties of the 9Cr-ODS steel samples with different Y2O3 contents were also measured simultaneously. The experimental data show when Y2O3 content is 0.3%, the density of Y-Ti-O nano-clusters is the highest, reaching to 1.39×1024 /m3. At the same time, the number density of Y-Ti-O nano-clusters is the lowest, if the Y2O3 content is 0.7%. The XAFS result of 0.7% Y2O3 sample is close to a Y2O3 reference sample. The 0.3% Y2O3 has a bigger grain size than the other two samples. The 9Cr-ODS steels with Y2O3 content of 0.3% exhibit the highest tensile strength and higher ductility properties.