Kinetic approach for growth and coalescence of nano-size oxide particles in 9Cr-ODS steel using high-energy synchrotron radiation X-rays in SPring-8

Kim, S.-W.; Shobu, Takahisa  ; Otsuka, Satoshi   ; Kaito, Takeji ; Inoue, Masaki ; Onuma, Masato*

The size and density distribution of dispersed oxide particles is recognized as one of the main issues for ensuring good microstructural stability and high temperature strength in a high temperature (700 C) and neutron irradiation (250 dpa) environment. However, the behavior of oxide particles in the hot-solidification process has not been determined yet. This study evaluated the correlation between nano-size oxide particles and the heat treatment temperature and time in order to characterize the mechanism of formation and the behavior during growth and coalescence for these particles in 9Cr-ODS steel raw powder. XRD and SAXS measurements were made using high-energy synchrotron radiation X-rays in SPring-8. This is the first report of the oxide complex particles (YTiO and YTiO) being formed from 800 C to 960 C, and they were observed to grow and coalesce on increasing both heat-treatment temperature and time.