b'Nuclear Science User Facilities the APS beamline dose limit, whichto 30 seconds for diffraction pattern excluded irradiated materials. For theacquisition. To increase the data points microstructural studies, the samplesrecorded in the elastic deformation included samples prepared from bothregion, the second beamline experi-aged and pristine in-situ tensile frac- ment was conducted using a load-tured specimens (TEM), and irradiatedcontrol mode. A load step of 10 N in specimens with and without priorthe elastic region and 2050 N in the thermal aging (APT). plastic region were used. The mono-The research project is highly relevantchromatic X-ray with energy about to the DOE-NE Light Water Reactors52 keV ( = 0.2394 ) and beam size Sustainability Program, and its outcomeabout 400 m400 m was used for will significantly improve the scientificthe second experiment while the data understanding of the degradation ofacquisition process was the same as duplex-structure stainless steels inthat used in the first experiment.LWRs and contribute to the construc- The dislocation density in the frac-"NSUF offers a greattion of a physics-based model fortured tensile specimen was measured predicting material performance forby TEM for both unaged and aged reactor license renewal and regulation. conditions. TEM lamellae were lifted platform for conductingExperimental or from the gauge zone using a FEI Technical Approach HELIOS 600i focused ion beam (FIB). scientific researchAs shown in Figure 1a, the in-situThe dislocation density was measured WAXS tensile tests were conductedusing the scanning transmission using the 10-ID-B beamline at theelectron microscopy (STEM) mode at and training the nextAdvanced Photon Source (APS),selected zone axises. All TEM charac-Argonne National Laboratory (ANL).terization was performed using a FEI Tecnai F30 S/TEM at the Microscopy generation of work force." Two beamline experiments wereand Characterization Suite (MaCS) conducted using two different controlof the Center for Advanced Energy modes. For the first experiment, a - Yong Yangmonochromatic X-ray beam with anStudies (CAES) in Idaho Falls, ID.energy of about 64 keV ( = 0.1925APT characterizations were conducted ) and a beam size about 600 m to quantify the spinodal decomposi-600 m was employed. The specimention and G-phase precipitates in the was strained incrementally until frac- ferrite phase of neutron irradiated ture while operating in a displacementCF-8 cast stainless steel. Reconstruc-control mode. A displacement step oftions and analyses were performed 0.001 mm in the elastic region andusing Cameca\'s Integrated Visualiza-0.050.10 mm in the plastic regiontion and Analysis software 3.8.0 was employed. X-ray-diffraction(IVAS). Three-dimensional (3-D) patterns were acquired after eachreconstructions were conducted by displacement step using the mar345following the standard procedure of image-plate X-ray detector. To maxi- Recon Wizard in the software, and mize the signal-to-noise ratio withoutSEM tip images were used to define saturation, the exposure time was settip profiles.48'