2011 Volume 31 Issue 122 Pages 98-103
Oxide-dispersion-strengthened (ODS) 9Cr ferritic heat resistant steel is a leading candidate for a cladding material used in advanced fast reactor fuels because of its superior radiation resistance and high-temperature strength. In this study, distribution of oxides, which is presumed to be a dominant factor of the high-temperature strength, has been evaluated by three-dimensional (3D) observations using electron tomography. The oxide distribution was classified into two regions, whose number densities were high or low. Dislocation pinning forces caused by the oxides were estimated from the 3D data in each region. A good coincidence was recognized between the force in the low-density region and a threshold stress at which the creep deformation mechanism changes. Therefore, the high temperature deformation behavior of ODS steels is influenced by dislocation motions in the low-density regions of oxides.
