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a b s t r a c tAn oxide dispersion-strengthened (ODS) 316 steel was developed to simultaneously provide the advantages of ODS steels in mechanical strength and radiation tolerance as well as the excellence of austenitic steels in creep performance and corrosion resistance. The precipitate phases within the austenite matrix were identified by the combined techniques of atom probe tomography (APT), scanning transmission electron microscopy equipped with electron dispersive X-ray spectroscopy (STEM-EDS), and synchrotron wide-angle and small-angle X-ray scattering (WAXS and SAXS). Coarse TiN, hexagonal YAlO 3 and orthorhombic YAlO 3 precipitates were found along with fine Y-Ti-O nanoparticles. In situ WAXS experiments were performed at room and elevated temperatures to examine the size effect on the load partitioning phenomenon for TiN, hexagonal YAlO 3 and Y 2 Ti 2 O 7 phases. In addition, the dislocation density evolution throughout the tensile tests was analyzed by the modified Williamson-Hall method and confirmed by transmission electron microscopy (TEM) observations, revealing the difference in plasticity at various temperatures.

Austenitic oxide dispersion-strengthened (ODS) alloys provide excellent mechanical strength and radiation tolerance along with their intrinsic advantages in corrosion resistance and high temperature creep resistance. This paper reports the in-situ synchrotron X-ray diffraction (XRD) tensile test results of ODS 304 stainless steel specimens. The oxygen-enriched nanoparticles were first characterized by both atom probe tomography (APT) and analytic scanning transmission electron microscopy (STEM). Three different types of precipitate phases were recognized, including large scale (around 100nm) TiN, intermediate scale (around 20nm) Y-Al-O, and small scale (< 5nm) Y-Ti-O. The lattice responses of different phases within the alloy to the externally applied stress indicates a prominent load partitioning phenomenon. This phenomenon was found to be highly dependent on the size of the precipitates. In addition, deformation-induced martensitic transformation was examined by the modified Williamson-Hall analyses of peak broadening, and was found to be different from that in ordinary 304 stainless steel.

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