Nanocrystalline oxide dispersion strengthened （ODS） ferritic steel powders with nominal composition of Fe-14Cr-3W-0.3Ti-0.4Y2O3 are synthesized using sol-gel method and hy- drogen reduction. At low reduction temperature the impurity phase of CrO is detected. At higher reduction temperature the impurity phase is Cr2O3 which eventually disappears with increasing reduction time. A pure ODS ferritic steel phase is obtained after reducing the sol-gel resultant products at 1200℃ for 3 h. The HRTEM and EDS mapping indicate that the Y2O3 particles with a size of about 15 nm are homogenously dispersed in the alloy matrix. The bulk ODS ferritic steel samples prepared from such powders exhibit good mechanical performance with an ultimate tensile stress of 960 MPa.
China reduced-activation ferritic/martensitic steel is irradiated at 773 K with 792 MeV Ar-ions to fluences of 2.3×10^20 and 4.6×10^20 ions/m2, respectively. The variation of the microstructures of the Reduced-activation ferritic/martensitic （RAFM） steel samples with the Ar-ion penetration depth is investigated using a transmission electron microscope （TEM）. Prom analyses of the microstrueture changes along with the Ar-ions penetrating depth, it is found that high-density cavities form in the peak damage region. The average size and the number density of the cavities depend strongly on the damage level and Ar-atom concentration. Swelling due to the formation of cavities increases significantly with an increased damage level, and the existence of deposited Ar-atoms also enhances the growth of the average size of the cavities. The effect of atom displacements and Ar-atoms on the swelling of the RAFM steel under high energy Ar-ion irradiation is discussed briefly.
Austenitic stainless steels are a class structural material applied in current nuclear reactors and spallation targetsas well as future nuclear devices. It is well known, the migration and interaction of defects and their clusters andsmall dislocation loops caused by irradiation induce changes in mechanical properties of materials and result inradiation hardening and ductility loss of materials. In the present study, microstructure evolution in EC316LNaustenitic steel irradiated with mixed spectra of high-energy proton and spallation neutrons has been investigatedby using Transmission Electron Microscopy (TEM).
