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Ecker, Lynne

Publications and source records attributed to Ecker, Lynne.

8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Three-dimensional strain imaging of irradiated chromium using multi-reflection Bragg coherent diffraction

Abstract Radiation-induced materials degradation is a key concern in limiting the performance of nuclear materials. The formation of nanoscale void and gas bubble superlattices in metals and alloys under radiation environments can effectively mitigate radiation-induced damage, such as swelling and aid the development of next generation radiation tolerant materials. To effectively manage radiation-induced damage via superlattice formation, it is critical to understand the microstructural changes and strain induced by such superlattices. We utilize multi-reflection Bragg coherent diffraction imaging to quantify the full strain tensor induced by void superlattices in iron irradiated chromium substrate. Our approach provides a quantitative estimation of radiation-induced three-dimensional (3D) strain generated at the microscopic level and predicts the number density of defects with a high degree of sensitivity. Such quantitative evaluation of 3D strain in nuclear materials can have a major impact on predicting materials behavior in radiation environments and can revolutionize design of radiation tolerant materials.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Analysis of inconel 600 oxidized under loss-of-coolant accident conditions: A multi-modal approach

Understanding the performance of cladding materials during a loss-of-coolant accident scenario is crucial for developing next-generation accident tolerant nuclear fuel rod claddings. We describe a multi-modal approach combining synchrotron-based diffraction, and Raman spectroscopy with nano-scale electron microscopy techniques for investigating oxidation of Inconel 600 (A600) in steam and air environments at 1200 °C for 2 h. We report that A600 exposed to steam develops a Cr 2 O 3 -enriched surface layer while a mixed phase oxide layer containing NiFe 2 O 4 , Cr 2 O 3 , Fe 3 O 4 and Fe (3–x) CrxO 4 is formed in air. Mechanism of oxidation for A600 in air and steam environments is discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Unraveling the Early-Stage Ordering of Krypton Solid Bubbles in Molybdenum: A Multimodal Study

Self-organization of defects such as fission gas bubbles in materials can lead to high inventory capacity for fission gas storage and help mitigate swelling caused by fission gases in nuclear fuel materials under radiation in nuclear reactors. Here, we report the physical mechanism of self-organization of krypton (Kr) gas bubbles in molybdenum (Mo) under ion implantation. The ion fluence and temperature-dependent formation of Kr solid bubble superlattice (SBS) in Mo were investigated by using both synchrotron-based small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Early stage self-organization of gas bubbles is observed at a fluence of 2.5 × 10 16 ions/cm 2 at temperatures of 300–400 °C. The bubble lattice constant increases with increasing implantation temperature from 300 to 400 °C. Both experiments and atomic kinetic Monte Carlo modeling indicate that the Kr solid bubbles are weakly ordered in comparison to previously studied helium (He) gas bubble superlattice (GBS) while the lattice constant are relatively smaller for Kr SBS compared to that of He GBS. The irradiation conditions suggest that spinodal decomposition, which is a form of phase separation, probably precedes gas bubble ordering in Mo. Altogether, our work sheds light on the formation mechanism of noble gas superlattice toward the development of radiation-tolerant materials which are important for the design of advanced nuclear reactors.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Structural and chemical changes from CO2 exposure to self-healing polymer cement composites for geothermal wellbores

Wellbore cement is subjected to a number of mechanical, thermal and chemical stress regimes over its lifetime. Therefore, next generation wellbore cement formulations need to be evaluated in conditions relevant to these environments. In this work, we investigate the mechanism of the alteration of a novel self-healing polymer-cement composite recently reported by our group after exposure to a CO2-rich environment by using synchrotron based X-ray Fluorescence (XRF) and X-ray absorption near edge structure (XANES) and scanning electron microscopy coupled with energy dispersive spectroscopy. Results showed that chemical alteration of the polymer-cement follows the rim carbonation mechanism, similar to conventional cement although carbonation takes place to a lesser extent in polymer-cements despite the higher porosity. Along with detailed mechanistic insights on carbonation in polymer-cement composite, the performance of these in CO2-rich environment is further studied using standard compressive strength analysis.

Elbakhshwan, Mohamed↗
DOE OSTI2020

Radioactive Material Dynamics @ NSLS-II [Slides]

RMD @ NSLS-II helps pave the path to a DMMSC: Developing expertise in techniques and experimental methods for DMMSC science; Improving capabilities for models to become microstructurally aware; Workforce training and development; Help refine DMMSC scientific requirements; Complementary to DMMSC XFEL science (EDXD/EXAFS)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗