@article{harilal_kautz_2024, title={Analysis of hydrogen and lithium isotopes using laser-induced breakdown spectroscopy}, volume={12939}, ISBN={["978-1-5106-7184-3"]}, ISSN={["1996-756X"]}, DOI={10.1117/12.3015929}, journal={HIGH-POWER LASER ABLATION VIII}, author={Harilal, S. S. and Kautz, E. J.}, year={2024} }
 @article{harilal_shaik_kautz_devaraj_casella_senor_2024, title={Detection of tritium using ultrafast laser-induced breakdown spectroscopy}, volume={2}, ISSN={["1364-5544"]}, url={https://doi.org/10.1039/D3JA00439B}, DOI={10.1039/D3JA00439B}, abstractNote={Detection of protium, deuterium and tritium using ultrafast LIBS with rapid, and standoff capability in addition to no sample preparation requirement which are crucial to nuclear nonproliferation, safeguards, and security}, journal={JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY}, author={Harilal, Sivanandan S. and Shaik, Abdul K. and Kautz, Elizabeth J. and Devaraj, Arun and Casella, Andrew M. and Senor, David J.}, year={2024}, month={Feb} }
 @article{kautz_polek_ronnebro_harilal_2024, title={Enhancing analytical merits of laser-induced breakdown spectroscopy of hydrogen isotopes using an orthogonal double-pulsing scheme}, volume={217}, ISSN={["1873-3565"]}, DOI={10.1016/j.sab.2024.106952}, abstractNote={Accurate detection and quantification of hydrogen isotopes in solid materials are vital for diverse applications, including fusion energy, hydrogen storage, and tritium production. Laser-induced breakdown spectroscopy (LIBS) is a well-established, rapid, standoff method for this purpose, but it faces challenges related to the analytical merits required for isotopic analyses. In this study, we enhance the analytical and detection capabilities of traditional single-pulse LIBS by implementing an orthogonal double pulsing approach, focusing on the analysis of a range of 2H concentrations in Zircaloy-4 substrates (acting as a proxy for 3H). The double-pulse experiments employed an orthogonal re-heating configuration with two nanosecond Nd:YAG lasers. We systematically evaluated critical parameters affecting the signal intensity in double-pulse LIBS, including interpulse delay, ambient gas pressure, and heating laser energy. Our results demonstrate that employing an orthogonal double-pulse scheme significantly enhances 2Hα emission while minimizing line broadening and self-absorption, ultimately improving the technique's analytical capabilities.}, journal={SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY}, author={Kautz, Elizabeth J. and Polek, Mathew P. and Ronnebro, Ewa C. E. and Harilal, Sivanandan S.}, year={2024}, month={Jul} }
 @article{gwalani_martin_kautz_guo_lambeets_olszta_battu_malakar_yang_guo_et al._2024, title={Mechanistic understanding of speciated oxide growth in high entropy alloys}, volume={15}, ISSN={["2041-1723"]}, DOI={10.1038/s41467-024-49243-8}, abstractNote={Complex multi-element alloys are gaining prominence for structural applications, supplementing steels, and superalloys. Understanding the impact of each element on alloy surfaces due to oxidation is vital in maintaining material integrity. This study investigates oxidation mechanisms in these alloys using a model five-element equiatomic CoCrFeNiMn alloy, in a controlled oxygen environment. The oxidation-induced surface changes correlate with each element's interactive tendencies with the environment, guided by thermodynamics. Initial oxidation stages follow atomic size and redox potential, with the latter becoming dominant over time, causing composition inversion. The study employs in-situ atom probe tomography, transmission electron microscopy, and X-ray absorption near-edge structure techniques to elucidate the oxidation process and surface oxide structure evolution. Our findings deconvolute the mechanism for compositional and structural changes in the oxide film and will pave the way for a predictive design of complex alloys with improved resistance to oxidation under extreme conditions.}, number={1}, journal={NATURE COMMUNICATIONS}, author={Gwalani, Bharat and Martin, Andrew and Kautz, Elizabeth and Guo, Boyu and Lambeets, S. V. and Olszta, Matthew and Battu, Anil Krishna and Malakar, Aniruddha and Yang, Feipeng and Guo, Jinghua and et al.}, year={2024}, month={Jun} }
 @article{shaik_polek_kautz_casella_senor_harilal_2024, title={The influence of laser energy on deuterium emission characteristics from a Zircaloy-4 plasma}, url={https://doi.org/10.1063/5.0220128}, DOI={10.1063/5.0220128}, abstractNote={Laser-produced plasma coupled with optical emission spectroscopy (OES) is a promising technique for detecting certain isotopes, with unique capabilities such as standoff and rapid detection and minimal to no sample preparation requirements. The key figure-of-merit for isotopic analysis using optical spectroscopy tools is the linewidth relative to the isotope shift. Although the isotopes of hydrogen (1H, 2H, and 3H) possess large isotopic shifts (1H–2H ≈ 180 pm, 1H–3H ≈ 240 pm), being a light element, the H transitions are susceptible to various broadening mechanisms in the plasma environment. One of the critical parameters that influence the linewidth of a transition in an LPP is the incident laser energy. In the present study, we evaluated the role of laser energy on plume expansion dynamics, deuterium emission intensity, and linewidth in a nanosecond laser-produced Zircaloy-4 plasma. The changes in 2Hα emission intensity and linewidth were investigated for varying laser fluence and time after plasma onset. Spatially resolved and spatially integrated OES were performed and compared to investigate the emission spectral features and linewidth of 2Hα. Monochromatic two-dimensional time-resolved imaging was also performed to understand the morphology of the deuterium and protium emission relative to all species in the plume. Our results showed that 1Hα and 2Hα emissions predominantly occur closer to the target. Measurements of 2Hα linewidth approached similar values at later times of plasma evolution regardless of the laser energy. The linewidths of the 2Hα transition showed insignificant differences between spatially resolved and spatially integrated measurements.}, journal={Physics of Plasmas}, author={Shaik, A. K. and Polek, M. P. and Kautz, E. J. and Casella, A. M. and Senor, D. J. and Harilal, S. S.}, year={2024}, month={Oct} }
 @article{kautz_phillips_diwakar_zelenyuk_harilal_2023, title={Comparing the kinetics of ionized and neutral atoms from single and multi-element laser-produced plasmas}, volume={30}, ISSN={["1089-7674"]}, url={https://doi.org/10.1063/5.0146958}, DOI={10.1063/5.0146958}, abstractNote={Kinetics of ion and neutral atom emission features were compared for nanosecond laser-produced plasmas generated from several metal targets (i.e., Al, Ti, Zr, Nb, Ta) and an alloy containing all of these as principal alloying elements. Plasmas were produced by focusing 6 ns, 1064 nm pulses from an Nd:YAG laser on the targets of interest in a vacuum. A Faraday cup was used for collecting ion temporal features while spatially and temporally resolved emission spectroscopy was used for measuring the optical time of flight of various neutral atomic transitions. Our results highlight that most probable ion and atom velocities decay with increasing atomic mass. Trends for ions from the alloy target represent a weighted average where all ions contribute. For both ions and atoms, velocities decrease with increasing heat of vaporization and melting temperature, consistent with the thermal mechanisms that contribute to nanosecond laser ablation. Kinetic energies for neutral atoms from pure metal targets have some variability with atomic mass, whereas kinetic energies for atoms from the alloy target are more similar. These more similar kinetic energies observed for neutral atoms in the multi-element plasma may be attributed to collisions between species from all elements in the Knudsen layer.}, number={5}, journal={PHYSICS OF PLASMAS}, author={Kautz, Elizabeth J. J. and Phillips, Mark C. C. and Diwakar, Prasoon K. K. and Zelenyuk, Alla and Harilal, Sivanandan S. S.}, year={2023}, month={May} }
 @article{phillips_kautz_harilal_2023, title={Comparison of excitation and kinetic temperatures in a laser-produced plasma using absorption spectroscopy}, volume={48}, ISSN={["1539-4794"]}, url={https://doi.org/10.1364/OL.487910}, DOI={10.1364/OL.487910}, abstractNote={High-resolution tunable laser absorption spectroscopy is used to
					measure time-resolved absorption spectra for six neutral uranium
					transitions in a laser-produced plasma. Analysis of the spectra shows
					that kinetic temperatures are similar for all six transitions, but
					excitation temperatures are higher than kinetic temperatures from
					10–100 μs, indicating departures from local
					thermodynamic equilibrium.}, number={7}, journal={OPTICS LETTERS}, author={Phillips, Mark c. and Kautz, Elizabeth j. and Harilal, Sivanandan s.}, year={2023}, month={Apr}, pages={1942–1945} }
 @article{polek_kautz_ahmed_kowash_beg_harilal_2023, title={Experimental and theoretical comparison of ion properties from nanosecond laser-produced plasmas of metal targets}, url={https://doi.org/10.1063/5.0146428}, DOI={10.1063/5.0146428}, abstractNote={The ion emission properties of laser-produced plasmas as a function of laser intensities between 4–50 GW cm−2 and varying angles with respect to the target normal were investigated. The plasmas were produced by focusing 1064 nm, 6 ns pulses from an Nd:YAG laser on various metal targets. The targets used for this study include Ti, Mo, and Gd (Z=22,42,64). It is noted that all ion profiles are composed of multiple peaks—a prompt emission peak trailed by three ion peaks (ultrafast, fast, and thermal). Experimentally, it is shown that each of these ion peaks follows a unique trend as a function of laser intensity, angle, and distance away from the target. Theoretically, it is shown that simple analytical models can be used to explain the properties of the ions. The variations in the ion velocity and density as a function of laser intensity are found to be in good agreement with theoretical models of sheath acceleration, isothermal self-similar expansion, and ablative plasma flow for various ion peaks.}, journal={Journal of Applied Physics}, author={Polek, M. P. and Kautz, E. J. and Ahmed, T. and Kowash, B. R. and Beg, F. N. and Harilal, S. S.}, year={2023}, month={May} }
 @article{kautz_zelenyuk_gwalani_olszta_phillips_manard_kimblin_harilal_2023, title={Impact of environmental oxygen on nanoparticle formation and agglomeration in aluminum laser ablation plumes}, volume={159}, ISSN={["1089-7690"]}, url={https://doi.org/10.1063/5.0167400}, DOI={10.1063/5.0167400}, abstractNote={The role of ambient oxygen gas (O2) on molecular and nanoparticle formation and agglomeration was studied in laser ablation plumes. As a lab-scale surrogate to a high explosion detonation event, nanosecond laser ablation of an aluminum alloy (AA6061) target was performed in atmospheric pressure conditions. Optical emission spectroscopy and two mass spectrometry techniques were used to monitor the early to late stages of plasma generation to track the evolution of atoms, molecules, clusters, nanoparticles, and agglomerates. The experiments were performed under atmospheric pressure air, atmospheric pressure nitrogen, and 20% and 5% O2 (balance N2), the latter specifically with in situ mass spectrometry. Electron microscopy was performed ex situ to identify crystal structure and elemental distributions in individual nanoparticles. We find that the presence of ≈20% O2 leads to strong AlO emission, whereas in a flowing N2 environment (with trace O2), AlN and strong, unreacted Al emissions are present. In situ mass spectrometry reveals that as O2 availability increases, Al oxide cluster size increases. Nanoparticle agglomerates formed in air are found to be larger than those formed under N2 gas. High-resolution transmission electron microscopy demonstrates that Al2O3 and AlN nanoparticle agglomerates are formed in both environments; indicating that the presence of trace O2 can lead to Al2O3 nanoparticle formation. The present results highlight that the availability of O2 in the ambient gas significantly impacts spectral signatures, cluster size, and nanoparticle agglomeration behavior. These results are relevant to understanding debris formation in an explosion event, and interpreting data from forensic investigations.}, number={17}, journal={JOURNAL OF CHEMICAL PHYSICS}, author={Kautz, Elizabeth J. and Zelenyuk, Alla and Gwalani, Bharat and Olszta, Matthew J. and Phillips, Mark C. and Manard, Manuel J. and Kimblin, Clare W. and Harilal, Sivanandan S.}, year={2023}, month={Nov} }
 @article{kautz_xu_harilal_polek_casella_senor_harilal_2023, title={Influence of ambient gas on self-reversal in Li transitions relevant to isotopic analysis}, url={https://doi.org/10.1364/OE.477990}, DOI={10.1364/OE.477990}, abstractNote={Laser induced breakdown spectroscopy is a promising, rapid analysis method for the detection and quantification of Li and its isotopes needed in geochemical, nuclear, and energy storage applications. However, spectral broadening in laser produced plasmas, presence of fine and hyperfine structures, and self-reversal effects make Li isotopic analysis via laser induced breakdown spectroscopy challenging. The present study explores the influence of Ar, N2, and He ambient gases over the pressure range of 0.05 - 100 Torr on line broadening and self-reversal of the Li I transition with the greatest isotopic shift in the VIS spectral region (i.e., ≈670.8 nm, ≈15.8 pm isotopic shift). We perform spatially and temporally resolved optical emission spectroscopy of plasmas produced via laser ablation of LiAlO2 substrates. Our results show that the self-reversal and linewidth is reduced at lower pressures for all gases, and using optimized plasma conditions with chemometric methods, the 6Li/7Li isotopic ratios can be predicted.}, journal={Optics Express}, author={Kautz, Elizabeth J. and Xu, Annie and Harilal, Ajay V. and Polek, Mathew P. and Casella, Andrew M. and Senor, David J. and Harilal, Sivanandan S.}, year={2023}, month={Jan} }
 @article{kautz_song_riechers_koziol_briggs_yano_prabhakaran_schemer-kohrn_soulami_joshi_et al._2023, title={Influence of processing on secondary phase formation and microstructural evolution at U-10Mo alloy and Zr interlayer interfaces}, volume={969}, ISSN={["1873-4669"]}, DOI={10.1016/j.jallcom.2023.172074}, abstractNote={Thermo-mechanical processing of uranium-10 wt% molybdenum (U-10Mo) alloy fuel plates with a zirconium (Zr) interlayer leads to microstructure changes at fuel/interlayer interfaces. Secondary phases formed at this interface are particularly important to interfacial bond strength, process optimization, and maintaining structural integrity of the fuel plates during irradiation. In this work, we determined the phases and phase transformation products occurring at the interface of the U-10Mo fuel and Zr interlayer when fuel plates are subjected to short and long hot isostatic pressing (HIP) cycles. Interfacial morphology, crystal structure and composition of phases formed, and relative hardness across the U-10Mo/Zr interfaces were studied using a multi-length scale, multi-modal characterization approach involving electron microscopy, atom probe tomography, and atomic force microscopy. Results highlight that the extent of phase transformations, secondary phase formation, and hardness variability across interfaces can be controlled by modifying processing parameters. In addition, phases formed at U-10Mo/Zr interfaces are similar for both HIP process conditions, however, phase distribution, interface thickness, and relative hardness vary significantly. The extent of the discontinuous precipitation reaction leading to α-U formation is also impacted by temperature and pressure in the HIP step; greater time at elevated temperature/pressure increases extent of the DP reaction.}, journal={JOURNAL OF ALLOYS AND COMPOUNDS}, author={Kautz, Elizabeth J. and Song, Miao and Riechers, Shawn and Koziol, Adam and Briggs, Samuel A. and Yano, Kayla and Prabhakaran, Ramprashad and Schemer-Kohrn, Alan and Soulami, Ayoub and Joshi, Vineet V. and et al.}, year={2023}, month={Dec} }
 @misc{kautz_gwalani_yu_varga_geelhood_devaraj_senor_2023, title={Investigating zirconium alloy corrosion with advanced experimental techniques: A review}, volume={585}, ISSN={["1873-4820"]}, DOI={10.1016/j.jnucmat.2023.154586}, abstractNote={Zirconium-based alloys (Zr alloys) are key materials in the nuclear industry due to their thermal stability, mechanical durability, and low thermal neutron cross section. However, corrosion can significantly impact their integrity and lifespan. The corrosion of Zr alloys involves dynamic processes such as phase transformations, element redistributions, stress accumulation, volumetric changes, and formation of defects in oxide films. Recent advancements in experimental techniques have improved our understanding of these phenomena and our ability to predict material behavior in extreme environments. This review focuses on the knowledge gained through the application of advanced experimental techniques to enhance the understanding of zirconium alloy oxidation and hydrogen pick-up in nuclear environments.}, journal={JOURNAL OF NUCLEAR MATERIALS}, author={Kautz, Elizabeth and Gwalani, Bharat and Yu, Zefeng and Varga, Tamas and Geelhood, Kenneth and Devaraj, Arun and Senor, David}, year={2023}, month={Nov} }
 @article{yu_kautz_zhang_schneider_kim_zhang_lambeets_devaraj_couet_2023, title={Irradiation damage reduces alloy corrosion rate via oxide space charge compensation effects}, url={https://doi.org/10.1016/j.actamat.2023.118956}, DOI={10.1016/j.actamat.2023.118956}, abstractNote={Radiation effects in materials often compound and accelerate other detrimental phenomena such as embrittlement, oxidation and creep. However, irradiation can also decrease the oxidation rate, for instance with ZrNb alloys nuclear fuel cladding. In this study, we rationalize this observation on Zr-0.5Nb alloy by introducing a mechanism based on oxide space charge modification, resulting from irradiation enhanced Nb clustering. This mechanism is investigated using a multiscale approach: from the macroscale, to determine post-irradiation oxidation kinetics, to the atomic scale, using in-situ atom probe tomography sample oxidation, to observe elemental solute redistribution across the oxide/metal interface. The mechanism is further supported by high resolution transmission electron microscopy characterization and density functional theory calculations. A point defect model is proposed to account for oxide space charge effects and their changes under irradiation. This integrated, multiscale experimental and modeling approach challenges the current paradigm on irradiation effects and how they can potentially improve materials performance in extreme environments.}, journal={Acta Materialia}, author={Yu, Zefeng and Kautz, Elizabeth and Zhang, Hongliang and Schneider, Anton and Kim, Taeho and Zhang, Yongfeng and Lambeets, Sten and Devaraj, Arun and Couet, Adrien}, year={2023}, month={Jul} }
 @article{koziol_yano_schemer-kohrn_soulami_joshi_briggs_kautz_2023, title={Microstructure and microchemistry changes at U-10Mo fuel/AA6061 cladding interfaces with varying hot isostatic pressing conditions}, volume={585}, ISSN={["1873-4820"]}, url={https://doi.org/10.1016/j.jnucmat.2023.154597}, DOI={10.1016/j.jnucmat.2023.154597}, abstractNote={Monolithic uranium - 10 wt.% molybdenum (U-10Mo) is a promising high-assay low-enriched uranium fuel system for nuclear reactors used in research, medical isotope production, and remote power applications. During manufacturing, an aluminum alloy (AA6061) cladding is bonded to the U-10Mo fuel plate via hot isostatic pressing, during which diffusion and fuel/cladding chemical interaction occurs at plate edges. The microstructure and microchemistry changes that occur at fuel/cladding interfaces are important to understand as a function of process parameters to develop a reliable fuel fabrication process and to meet the desired specifications. Here, microstructural and microchemical changes are studied using complementary electron microscopy and atom probe tomography for two manufactured fuel plates with varied hot isostatic pressing (HIP) parameters. Results highlight that modifying thermomechanical processing parameters significantly changes the interaction layer thickness between U-10Mo and AA6061 by an order of magnitude. In addition, the distribution and concentration of elements (i.e., Al, Si, Mg) from cladding to fuel are investigated.}, journal={JOURNAL OF NUCLEAR MATERIALS}, author={Koziol, Adam and Yano, Kayla and Schemer-Kohrn, Alan and Soulami, Ayoub and Joshi, Vineet V. and Briggs, Samuel A. and Kautz, Elizabeth J.}, year={2023}, month={Nov} }
 @article{taylor_yano_sassi_matthews_kautz_lambeets_neuman_schreiber_wang_du_et al._2023, title={Resolving Diverse Oxygen Transport Pathways Across Sr‐Doped Lanthanum Ferrite and Metal‐Perovskite Heterostructures}, url={https://doi.org/10.1002/admi.202202276}, DOI={10.1002/admi.202202276}, abstractNote={AbstractPerovskite structured transition metal oxides are important technological materials for catalysis and solid oxide fuel cell applications. Their functionality often depends on oxygen diffusivity and mobility through complex oxide heterostructures, which can be significantly impacted by structural and chemical modifications, such as doping. Further, when utilized within electrochemical cells, interfacial reactions with other components (e.g., Ni‐ and Cr‐based alloy electrodes and interconnects) can influence the perovskite's reactivity and ion transport, leading to complex dependencies that are difficult to control in real‐world environments. Here, this work uses isotopic tracers and atom probe tomography to directly visualize oxygen diffusion and transport pathways across perovskite and metal‐perovskite heterostructures, that is, (Ni‐Cr coated) Sr‐doped lanthanum ferrite (La0.5Sr0.5FeO3; LSFO). Annealing in 18O2(g) results in elemental and isotopic redistributions through oxygen exchange (OE) in the LSFO while Ni‐Cr undergoes oxidation via multiple mechanisms and transport pathways. Complementary density functional theory calculations at experimental conditions provide rationale for OE reaction mechanisms and reveal a complex interplay of different thermodynamic and kinetic drivers. These results shed light on the fundamental coupling of defects and oxygen transport in an important class of catalytic materials.}, journal={Advanced Materials Interfaces}, author={Taylor, Sandra D. and Yano, Kayla H. and Sassi, Michel and Matthews, Bethany E. and Kautz, Elizabeth J. and Lambeets, Sten V. and Neuman, Sydney and Schreiber, Daniel K. and Wang, Le and Du, Yingge and et al.}, year={2023}, month={Mar} }
 @article{kautz_phillips_harilal_2023, title={Tantalum oxide and nitride spectral features from a laser-produced plasma}, volume={203}, ISSN={["1873-3565"]}, DOI={10.1016/j.sab.2023.106659}, abstractNote={We report measurements of time-resolved Ta, TaO and TaN emission spectroscopic signatures from a laser-produced plasma. Plasmas were generated using 1064 nm, 6 ns pulses from an Nd:YAG laser focused onto a pure Ta metal target in a gaseous environment with varying percentages of O2/N2 for controlling gas-phase oxidation/plasma chemistry. Time-resolved analysis showed that Ta oxide emission is prominent at later times in plasma evolution, whereas strong atomic emission is present at early times in air. Emission spectral features as a function of O2 partial pressure showed that TaO emission intensity increases, while the peak intensity of TaO appears earlier with increasing O2 availability. We also report emission spectra of TaN, and show that plasma chemistry favors TaO formation instead of TaN when O2 is present in the environment.}, journal={SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY}, author={Kautz, Elizabeth J. and Phillips, Mark C. and Harilal, Sivanandan S.}, year={2023}, month={May} }
 @article{mahajan_hasannaeimi_pole_kautz_gwalani_mukherjee_2022, title={Chemistry Dependence of Corrosion Mechanisms in Model Binary Metallic Glasses and Correlation with Electron Work Function}, ISSN={1556-5068}, url={http://dx.doi.org/10.2139/ssrn.4011828}, DOI={10.2139/ssrn.4011828}, abstractNote={Effect of chemistry change on corrosion mechanisms and passive film characteristics of model binary metallic glasses was studied. The corrosion current density decreased, and the corrosion potential increased towards nobler values with increase in phosphorus content for both Ni100-xPx and Co100-xPx amorphous systems (x = 10, 15, and 20 at. %). Scanning kelvin probe analysis showed an increase in volta potential for both the alloy systems with increase in phosphorus content. Enrichment of phosphorus in the passive layer was observed by advanced microscopy, which likely promoted the restoration of protective hypophosphite anion layer for the alloys with higher phosphorus content.}, journal={SSRN Electronic Journal}, publisher={Elsevier BV}, author={Mahajan, Chaitanya and Hasannaeimi, Vahid and Pole, Mayur and Kautz, Elizabeth J. and Gwalani, Bharat and Mukherjee, Sundeep}, year={2022} }
 @misc{phillips_kautz_harilal_2022, title={Combined Spatial, Temporal, and Spectral Analysis of Absorption and Emission in a Laser-Produced Plasma}, url={http://dx.doi.org/10.1109/icops45751.2022.9813007}, DOI={10.1109/icops45751.2022.9813007}, abstractNote={Spatio-temporal analysis of emission and absorption signatures of Al species in a nanosecond (ns) laser produced plasma (LPP) is presented. Plasmas were generated from an Inconel target containing Al by using 1064 nm, 6 ns full width half maximum pulses from an Nd:YAG laser at an Ar cover gas pressure of 34 Torr. Time-resolved emission and absorption (time-of-flight) from the Al I (394.4 nm) transition was collected from various spatial points within the plasma to study kinetics of the excited and ground state populations. Emission and absorption signatures showed multiple features in the temporal profiles appearing at different spatial locations and times after the plasma onset, including excitation of the Ar ambient gas, shock wave propagation, and plume expansion dynamics. Analysis of time- and space-resolved emission and absorption spectra were used to determine spectral linewidths, atomic number density, kinetic temperature, and excitation temperature. The results highlight that using time-of-flight measurements for high time- and space-resolution, combined with spectrally-resolved measurements to determine excitation temperatures and linewidths, provides a more complete picture of LPP spatiotemporal dynamics than is possible using each technique alone.}, journal={2022 IEEE International Conference on Plasma Science (ICOPS)}, publisher={IEEE}, author={Phillips, M. C. and Kautz, E. J. and Harilal, S. S.}, year={2022}, month={May} }
 @article{kautz_lambeets_royer_perea_harilal_devaraj_2022, title={Compositional partitioning during early stages of oxidation of a uranium-molybdenum alloy}, volume={212}, ISSN={1359-6462}, url={http://dx.doi.org/10.1016/j.scriptamat.2022.114528}, DOI={10.1016/j.scriptamat.2022.114528}, abstractNote={Compositional partitioning during uranium alloy oxidation was studied via complementary ex situ - in situ atom probe tomography. Nanoscopic volumes of uranium- 22 at. % molybdenum were exposed to air at room temperature/atmospheric pressure for 30–60 minutes (ex situ), and 300 ∘C - 10−5 mbar O2 gas for 2–5 minutes in a chemical reaction chamber attached to an atom probe system (in situ). For all environmental conditions, a hypostoichiometric uranium oxide is formed. Reaction fronts are observed at oxide/metal, oxide/hydride, and outer oxide/environment interfaces. Results reveal Mo redistributes across the oxide/metal interface, with a tendency for enrichment in the outer oxide. The formation of a hydrogen-rich subsurface layer between the oxide and base alloy accompanies oxidation in both air and oxygen gas environments. Carbon and silicon impurity elements also redistribute to the outer oxide, contributing to oxide film composition.}, journal={Scripta Materialia}, publisher={Elsevier BV}, author={Kautz, Elizabeth J. and Lambeets, Sten V. and Royer, Jacqueline and Perea, Daniel E. and Harilal, Sivanandan S. and Devaraj, Arun}, year={2022}, month={Apr}, pages={114528} }
 @article{mahajan_hasannaeimi_pole_kautz_gwalani_mukherjee_2022, title={Corrosion mechanisms in model binary metallic glass coatings on mild steel and correlation with electron work function}, volume={207}, ISSN={0010-938X}, url={http://dx.doi.org/10.1016/j.corsci.2022.110578}, DOI={10.1016/j.corsci.2022.110578}, abstractNote={Effect of chemistry change on corrosion mechanisms and passive film characteristics of model Ni-P and Co-P metallic glass coatings on mild steel was studied because of their simple chemistry and widespread use. Increase in phosphorus content led to improved corrosion resistance. Results indicated the presence of hypophosphite and phosphate anions on the corroded surfaces. Enrichment of phosphorus in the passive layer was observed, which likely promoted the restoration of the protective hypophosphite anion layer during dissolution. A correlation between electronic structure and corrosion resistance was established, with relative work function increasing with increase in phosphorus content.}, journal={Corrosion Science}, publisher={Elsevier BV}, author={Mahajan, Chaitanya and Hasannaeimi, Vahid and Pole, Mayur and Kautz, Elizabeth and Gwalani, Bharat and Mukherjee, Sundeep}, year={2022}, month={Oct}, pages={110578} }
 @misc{kautz_phillips_zelenyuk_harilal_2022, title={Evolutionary History of Atoms and Molecules in Reactive Laser-Produced Plasmas}, url={http://dx.doi.org/10.1109/icops45751.2022.9813306}, DOI={10.1109/icops45751.2022.9813306}, abstractNote={The kinetics of atoms and molecules in a laser-produced plasma were investigated for several metal targets (i.e., Al, Ti, Fe, Zr, Nb, and Ta). Plasmas from metal targets were generated by focusing 1064 nm, 6 ns pulses from an Nd:YAG laser. The initial physical conditions of the plasma were measured using emission spectroscopy. Gas-phase oxidation/plasma chemistry was initiated by adding partial pressures of O 2 (up to approximately 20 %) in an N 2 ambient environment. The dynamics of atomic and molecular species were monitored using space-resolved time-of-flight emission spectroscopy. Our results highlight that the partial pressure of O 2 strongly influences spectral features and molecular formation in laser-produced plasmas. Atoms and molecules co-exist in laser-produced plasmas, although with different temporal histories depending on target material due to differences in thermo- and plasma chemical reactions occurring in the plume.}, journal={2022 IEEE International Conference on Plasma Science (ICOPS)}, publisher={IEEE}, author={Kautz, E. J. and Phillips, M. C. and Zelenyuk, A. and Harilal, S. S.}, year={2022}, month={May} }
 @article{kautz_zelenyuk_gwalani_phillips_harilal_2022, title={Gas-phase oxidation and nanoparticle formation in multi-element laser ablation plumes}, volume={10}, ISSN={["1463-9084"]}, url={https://doi.org/10.1039/D2CP02437C}, DOI={10.1039/d2cp02437c}, abstractNote={Interaction of a multi-element laser produced plasma with air leads to formation of fractal agglomerates of nanoparticles consisting of multiple elements and their oxides.}, journal={PHYSICAL CHEMISTRY CHEMICAL PHYSICS}, author={Kautz, Elizabeth J. and Zelenyuk, Alla and Gwalani, Bharat and Phillips, Mark C. and Harilal, Sivanandan S.}, year={2022}, month={Oct} }
 @misc{polek_kautz_harilal_beg_2022, title={Investigation of Nanosecond Laser Ablation From Metal Targets}, url={http://dx.doi.org/10.1109/icops45751.2022.9813097}, DOI={10.1109/icops45751.2022.9813097}, abstractNote={Laser ablation has been used extensively in various applications, including EUV lithography, laser induced breakdown spectroscopy, inertial confinement fusion, nanoparticle generation, and many others [1] . In each application, optimization of laser and plasma parameters is required in order to maximize various attributes such as conversion efficiency, line emission, nanoparticle generation, etc. However, optimization of these attributes requires a detailed understanding of the fundamental processes that occur during laser-material interaction and plasma expansion. In this study, a 6 ns Nd:YAG laser with intensities up to 1E12 W/cm 2 is used to investigate the ion and electron properties of a laser produced plasma. In particular, the evolution of the ion flux and kinetic energy are studied at various distances and angles away from the target using a Faraday cup. Different materials are used to determine the effects of material properties on the ions. Electron densities and temperatures are measured using various spectroscopy techniques at different times and distances away from the target in order to characterize the early stages of plasma expansion. Experimental results are then compared to models, and the accuracy of the models is discussed.}, journal={2022 IEEE International Conference on Plasma Science (ICOPS)}, publisher={IEEE}, author={Polek, M. and Kautz, E. J. and Harilal, S. S. and Beg, F. N.}, year={2022}, month={May} }
 @misc{harilal_kautz_phillips_2022, title={Optical spectroscopic tools for standoff uranium detection}, url={http://dx.doi.org/10.1364/lacsea.2022.ltu4b.1}, DOI={10.1364/lacsea.2022.ltu4b.1}, abstractNote={Rapid and standoff analysis of uranium is important to many applications. We present the recent advances in standoff detection of uranium using emission and laser-induced fluorescence spectroscopy in conjunction with ultrafast laser filament ablation-based solid sampling.}, journal={Optical Sensors and Sensing Congress 2022 (AIS, LACSEA, Sensors, ES)}, publisher={Optica Publishing Group}, author={Harilal, Sivanandan S. and Kautz, Elizabeth J. and Phillips, Mark C.}, year={2022} }
 @article{kautz_phillips_zelenyuk_harilal_2022, title={Oxidation in laser-generated metal plumes}, url={https://doi.org/10.1063/5.0090155}, DOI={10.1063/5.0090155}, abstractNote={The temporal evolution of atoms and molecules in a laser-produced plasma was investigated using optical emission spectroscopy for several metal targets (i.e., Al, Ti, Fe, Zr, Nb, and Ta). Plasmas from metal targets were generated by focusing 1064 nm, 6 ns pulses from an Nd:YAG laser. Gas-phase oxidation/plasma chemistry was initiated by adding O2 (partial pressures up to ≈20%) to an N2 environment where the total background pressure was kept at a constant 1 atmosphere. Temporally resolved emission spectral features were used to track the gas-phase oxidation. The dynamics of atomic and molecular species were monitored using space-resolved time-of-flight emission spectroscopy. Our results highlight that the partial pressure of O2 strongly influences spectral features and molecular formation in laser-produced plasmas. Atoms and molecules co-exist in plasmas, although with different temporal histories depending on the target material due to differences in thermo- and plasma chemical reactions occurring in the plume.}, journal={Physics of Plasmas}, author={Kautz, Elizabeth J. and Phillips, Mark C. and Zelenyuk, Alla and Harilal, Sivanandan S.}, year={2022}, month={May} }
 @article{harilal_kautz_phillips_2022, title={Spatiotemporal evolution of emission and absorption signatures in a laser-produced plasma}, volume={131}, url={https://doi.org/10.1063/5.0081597}, DOI={10.1063/5.0081597}, abstractNote={We report spatiotemporal evolution of emission and absorption signatures of Al species in a nanosecond (ns) laser-produced plasma (LPP). The plasmas were generated from an Inconel target, which contained ∼0.4 wt. % Al, using 1064 nm, ≈6 ns full width half maximum pulses from an Nd:YAG laser at an Ar cover gas pressure of ≈34 Torr. The temporal distributions of the Al I (394.4 nm) transition were collected from various spatial points within the plasma employing time-of-flight (TOF) emission and laser absorption spectroscopy, and they provide kinetics of the excited state and ground state population of the selected transition. The emission and absorption signatures showed multiple peaks in their temporal profiles, although they appeared at different spatial locations and times after the plasma onset. The absorption temporal profiles showed an early time signature representing shock wave propagation into the ambient gas. We also used emission and absorption spectral features for measuring various physical properties of the plasma. The absorption spectral profiles are utilized for measuring linewidths, column density, and kinetic temperature, while emission spectra were used to measure excitation temperature. A comparison between excitation and kinetic temperature was made at various spatial points in the plasma. Our results highlight that the TOF measurements provide a resourceful tool for showing the spatiotemporal LPP dynamics with higher spatial and temporal resolution than is possible with spectral measurements but are difficult to interpret without additional information on excitation temperatures and linewidths. The combination of absorption and emission TOF and spectral measurements thus provides a more complete picture of LPP spatiotemporal dynamics than is possible using any one technique alone.}, number={6}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Harilal, S. S. and Kautz, E. J. and Phillips, M. C.}, year={2022}, month={Feb}, pages={063101} }
 @article{gerard_kautz_schreiber_han_mcdonnell_ogle_lu_saal_frankel_scully_2023, title={The role of chromium content in aqueous passivation of a non-equiatomic Ni38Fe20CrxMn21-0.5xCo21-0.5x multi-principal element alloy (x = 22, 14, 10, 6 at%) in acidic chloride solution}, url={https://doi.org/10.1016/j.actamat.2022.118607}, DOI={10.1016/j.actamat.2022.118607}, abstractNote={The effect of the Cr content on the corrosion behavior in a series of single-phase non-equiatomic Ni38Fe20CrxMn21-0.5xCo21-0.5x (6 < x < 22 at%) multi-principal element alloys (MPEAs) was investigated in acidified NaCl solutions. Comparisons were made with binary solid solution Co-Cr, Ni-Cr, and Fe-Cr alloys over a similar range of Cr contents. The corrosion behavior was evaluated using in-situ AC and DC electrochemical methods and ex-situ surface sensitive characterization techniques. Passivity and various levels of local corrosion resistance were obtained in the MPEA with 10 at% Cr or above. The binary Ni-Cr alloys with 12–30 at% Cr behaved similarly. The MPEA with 6 at% Cr and binary alloys with 5, 6, or 10 at% Cr were marginally passive or active and underwent localized corrosion during both linear sweep voltammetry and potentiostatic hold experiments. Passive films formed during potentiostatic hold experiments were characterized with X-ray photoelectron spectroscopy and atom probe tomography. Cr cation enrichment in the passive films was observed for all alloys and similar enrichment factors were obtained as a function of Cr content regardless of whether MPEA or binary alloy except for the Fe-Cr alloy. Moreover, passive current density was correlated with the Cr cation fraction in the passive film. The degree of Cr enrichment was attributed to a combination of thermodynamic and kinetic factors, such as selective chemical dissolution of alloying elements as well as limitation due to solute depletion at the metal oxide interface in alloys with a bulk Cr content ≤ 10 at%.}, journal={Acta Materialia}, author={Gerard, Angela Y. and Kautz, Elizabeth J. and Schreiber, Daniel K. and Han, Junsoo and McDonnell, Stephen and Ogle, Kevin and Lu, Pin and Saal, James E. and Frankel, Gerald S. and Scully, John R.}, year={2023}, month={Feb} }
 @article{baskaran_kautz_chowdhary_ma_yener_lewis_2021, title={Adoption of Image-Driven Machine Learning for Microstructure Characterization and Materials Design: A Perspective}, volume={73}, DOI={10.1007/s11837-021-04805-9}, abstractNote={The recent surge in the adoption of machine learning techniques for materials design, discovery, and characterization has resulted in increased interest in and application of image-driven machine learning (IDML) approaches. In this work, we review the application of IDML to the field of materials characterization. A hierarchy of six action steps is defined that compartmentalizes a problem statement into well-defined modules. The studies reviewed in this work are analyzed through the decisions adopted in them at each of these steps. Such a review permits a granular assessment of the field, for example, the impact of IDML on materials characterization at the nanoscale, the number of images in a typical dataset required to train a semantic segmentation model on electron microscopy images, the prevalence of transfer learning in the domain, etc. Finally, we discuss the importance of interpretability and explainability, and provide an overview of two emerging techniques in the field: semantic segmentation and generative adversarial networks.}, journal={JOM}, publisher={DJ Lewis}, author={Baskaran, A. and Kautz, E.J. and Chowdhary, A. and Ma, W. and Yener, B. and Lewis, D.J.}, year={2021}, pages={3639–3657} }
 @article{kautz_rönnebro_devaraj_senor_harilal_2021, title={Detection of hydrogen isotopes in Zircaloy-4 via femtosecond LIBS}, url={https://doi.org/10.1039/D1JA00034A}, DOI={10.1039/D1JA00034A}, abstractNote={Spatio-temporal mapping of species in a femtosecond laser induced Zircaloy-4 plasma identified conditions well-suited for the detection and analysis of deuterium across a wide range of concentrations.}, journal={Journal of Analytical Atomic Spectrometry}, publisher={Royal Society of Chemistry (RSC)}, author={Kautz, Elizabeth J. and Rönnebro, Ewa C. E. and Devaraj, Arun and Senor, David J. and Harilal, Sivanandan S.}, year={2021} }
 @article{kautz_shahrezaei_athon_frank_schemer-kohrn_soulami_lavender_joshi_devaraj_2021, title={Evaluating the microstructure and origin of nonmetallic inclusions in as-cast U-10Mo fuel}, url={https://doi.org/10.1016/j.jnucmat.2021.152949}, DOI={10.1016/j.jnucmat.2021.152949}, abstractNote={Low enriched uranium alloyed with 10 wt. % molybdenum (U-10Mo) has been identified as a promising alternative to highly enriched uranium oxide dispersion fuels for use in high performance research and test reactors. Manufacturing U-10Mo alloy fuel involves several complex thermomechanical processing steps and understanding of the microstructure and its evolution throughout the various fabrication steps is critical to enable the deployment of a reliable fuel production capability. Nonmetallic inclusions are often found in U castings and may affect subsequent fuel processing steps and microstructure evolution. Yet, the origin of these inclusions is not well established. To elucidate their origin and formation mechanisms, nonmetallic inclusions in U-10Mo castings were characterized on sub-nanometer to millimeter scale. Inclusion distribution, morphology, size, and composition were determined for the metallic fuel samples. Inclusions were estimated to comprise ~ 0.4 % of the fuel (by area), were identified at both grain boundaries and grain interiors, and were found to have varying morphologies (e.g., core-shell, elongated, blocky). All inclusions were either uranium carbides or oxides, or a combination of the two (i.e., dual-phase inclusions). Analysis of inclusions via atom probe tomography revealed that carbides and oxides were hypostoichiometric, with minor amounts of additional impurity elements present (e.g., Si, H). All analyzed inclusions were found to be enriched to ~20 at. % 235U, consistent with the surrounding γ-UMo matrix and target enrichment for the low enriched U fuel, indicating that the inclusions formed during the downblending of highly enriched U metal with depleted U via the melting and casting processes.}, journal={Journal of Nuclear Materials}, author={Kautz, Elizabeth J. and Shahrezaei, Sina and Athon, Matthew and Frank, Michael and Schemer-Kohrn, Alan and Soulami, Ayoub and Lavender, Curt and Joshi, Vineet V. and Devaraj, Arun}, year={2021}, month={Oct} }
 @misc{kautz_zelenyuk_gwalani_harilal_2021, title={Gas-phase molecular formation in multi-component laser-produced plasmas}, url={http://dx.doi.org/10.1109/icops36761.2021.9588337}, DOI={10.1109/icops36761.2021.9588337}, abstractNote={Chemistry evolution in transient plasma or fireball systems in air comprised of multiple elements is extremely complex, owing to numerous ionic, atomic, and molecular species present, overlapping spectral lines, and the gas-phase oxidation. Although plasma chemistry is widely studied for analytical and material detection applications, tracking the chemical evolution from atoms and ions to diatoms, polyatoms, and larger molecules, nanoparticles, and agglomerates in a multi-component system remains largely unexplored.}, journal={2021 IEEE International Conference on Plasma Science (ICOPS)}, publisher={IEEE}, author={Kautz, E. J. and Zelenyuk, A. and Gwalani, B. and Harilal, S. S.}, year={2021}, month={Sep} }
 @article{kautz_ma_baskaran_chowdhury_joshi_yener_lewis_2021, title={Image-driven discriminative and generative methods for establishing microstructure-processing relationships relevant to nuclear fuel processing pipelines}, volume={27}, ISSN={1431-9276 1435-8115}, url={http://dx.doi.org/10.1017/s1431927621007674}, DOI={10.1017/s1431927621007674}, abstractNote={Low enriched uranium alloyed with 10 wt. % molybdenum (U-10Mo) has been identified as a promising alternative to highly enriched uranium oxide dispersion fuels for use in high performance research and test reactors. Manufacturing U-10Mo alloy fuel involves several complex thermomechanical processing steps, as schematically described in Figure 1, and understanding of the microstructure and its evolution throughout the various fabrication steps is critical to enable the deployment of a reliable fuel production capability. This work explores the applicability of image-driven machine learning methods [1] to developing microstructure–processing relationships. Specifically, we seek to understand the role of several thermomechanical processing steps in the microstructure evolution observed in the U-10Mo system. An improved approach to determining microstructure–processing relationships is developed and presented, involving feature extraction, segmentation, and classification using a random forest model [2]. Microstructure image data are segmented to identify microstructural features of interest and quantify area fraction of these features, including the γ-UMo matrix, uranium carbide, and DP reaction transformation products. Several were explore of microstructure representations, how well information such as area fractions of phases, their spatial arrangement, and micrograph texture impact classification accuracies. We and Area are the area fraction of each phase/microstructural feature of interest. Spatial are by first measuring the}, number={S1}, journal={Microscopy and Microanalysis}, publisher={Oxford University Press (OUP)}, author={Kautz, Elizabeth and Ma, Wufei and Baskaran, Arun and Chowdhury, Aritra and Joshi, Vineet and Yener, Bulent and Lewis, Daniel}, year={2021}, month={Jul}, pages={2128–2130} }
 @article{kautz_phillips_harilal_2021, title={Laser-induced fluorescence of filament-produced plasmas}, url={https://doi.org/10.1063/5.0065240}, DOI={10.1063/5.0065240}, abstractNote={Self-guided ultrafast laser filaments are a promising method for laser beam delivery and plasma generation for standoff and remote detection of elements and isotopes via filament-induced breakdown spectroscopy (FIBS). Yet, there are several challenges associated with the practical application of FIBS, including delivery of sufficient laser energy at the target for generating plasma with a copious amount of emission signals for obtaining a high signal-to-noise ratio. Here, we use laser-induced fluorescence (LIF) to boost the emission signal and reduce self-reversal in the spectral profiles. Ultrafast laser filaments were used to produce plasmas from an Al 6061 alloy target at various standoff distances from 1 to 10 m. For LIF emission enhancement, a narrow linewidth continuous-wave laser was used in resonance with a 394.40 nm Al I resonant transition, and the emission signal was monitored from the directly coupled transition at 396.15 nm. Emission signal features of Al I are significantly enhanced by resonant excitation. In addition, LIF of filament ablation plumes reduces the self-reversal features seen in the thermally excited spectral profiles. Time-resolved two-dimensional fluorescence spectroscopy was performed for evaluating the optical saturation effects, which are found to be non-negligible due to high Al atomic densities in the filament-produced plasmas.}, journal={Journal of Applied Physics}, author={Kautz, Elizabeth J. and Phillips, Mark C. and Harilal, Sivanandan S.}, year={2021}, month={Nov} }
 @misc{kautz_yeak_phillips_harilal_2021, title={Laser-induced fluorescence of ultrafast laser filament generated plasmas for standoff detection}, url={http://dx.doi.org/10.1364/cleo_si.2021.sm1e.2}, DOI={10.1364/cleo_si.2021.sm1e.2}, abstractNote={Ultrafast laser filament produced plasmas are made at a standoff distance of ~ 10 m. The Al emission signal features are enhanced by resonant excitation employing a continuous-wave laser, and laser-induced fluorescence signals are measured. A comparison is made between the standoff signatures of LIBS and LIF emission.}, journal={Conference on Lasers and Electro-Optics}, publisher={Optica Publishing Group}, author={Kautz, Elizabeth J. and Yeak, Jeremy and Phillips, Mark C. and Harilal, Sivanandan S.}, year={2021} }
 @article{kautz_schreiber_devaraj_gwalani_2021, title={Mechanistic insights into selective oxidation and corrosion of multi-principal element alloys from high resolution and in situ microscopy}, volume={18}, url={https://doi.org/10.1016/j.mtla.2021.101148}, DOI={10.1016/j.mtla.2021.101148}, abstractNote={Multiple principal element alloys (MPEAs) have drawn significant recent interest from the metallurgical research community. These novel alloys have the potential to replace traditional alloys with a range of tailored mechanical properties, corrosion resistance, and radiation tolerance enabled by complex compositions. The broad alloy design space of MPEAs presents a great opportunity to discover new forms of oxidation and corrosion resistance in extreme environments that break away from conventional alloy design criteria. However, understanding the oxidation and corrosion response of MPEAs can be a challenging task due the complex compositional, structural, and chemical state changes occurring in the oxide or corrosion film and at its interface with the base alloy. This perspective discusses the utility of high resolution and in situ microscopy techniques for revealing unique aspects of MPEA oxidation and corrosion behavior at the atomic and near atomic scales. Challenges of studying oxidation and corrosion response of these alloys and several open questions are presented.}, journal={Materialia}, publisher={Elsevier BV}, author={Kautz, Elizabeth J. and Schreiber, Daniel K. and Devaraj, Arun and Gwalani, Bharat}, year={2021}, month={Aug}, pages={101148} }
 @article{ohodnicki_kautz_devaraj_yu_aronhime_krimer_mchenry_leary_2021, title={Nanostructure and compositional segregation of soft magnetic FeNi‐based nanocomposites with multiple nanocrystalline phases}, volume={36}, ISSN={0884-2914 2044-5326}, url={http://dx.doi.org/10.1557/s43578-020-00066-5}, DOI={10.1557/s43578-020-00066-5}, abstractNote={AbstractSoft magnetic metal amorphous nanocomposite alloys are produced through rapid solidification and thermal annealing yielding nanocrystals embedded within an amorphous precursor. Similar free energies in Co‐rich and FeNi‐based alloy systems result in multiple nanocrystalline phases being formed during devitrification. Studies of multi‐phase crystallization processes have been reported for Co‐rich alloys but relatively few have investigated FeNi‐based systems. A detailed characterization of compositional partitioning and microstructure of an optimally annealed FeNi‐based MANC (Fe70Ni30)80Nb4Si2B14 alloy is presented through complementary high‐resolution transmission electron microscopy (HRTEM) and atom probe tomography (APT). HRTEM demonstrates orientation relationships between FCC and BCC nanocrystals, suggesting heterogeneous nucleation of nanocrystals in the amorphous matrix or a cooperative mechanism of nucleation between BCC and FCC nanocrystallites. APT results show evidence for (i) the segregation of Fe and Ni between nanocrystals of different phases, (ii) B partitioning to the amorphous phase, and (iii) an Nb‐enriched shell surrounding nanocrystals.}, number={1}, journal={Journal of Materials Research}, publisher={Springer Science and Business Media LLC}, author={Ohodnicki, P. and Kautz, E.J. and Devaraj, A. and Yu, Y. and Aronhime, N. and Krimer, Y. and McHenry, M.E. and Leary, A.}, year={2021}, month={Jan}, pages={105–113} }
 @article{kautz_weerakkody_finko_curreli_koroglu_rose_weisz_crowhurst_radousky_demagistris_et al._2021, title={Optical spectroscopy and modeling of uranium gas-phase oxidation: Progress and perspectives}, volume={185}, url={https://doi.org/10.1016/j.sab.2021.106283}, DOI={10.1016/j.sab.2021.106283}, abstractNote={Studies related to U gas-phase oxidation through plasma- and thermo-chemistry are important for many fields, including environmental monitoring, forensic analysis, debris analysis in a weapon detonation event, and nucleation physics. Recently, significant efforts have been made to understand the chemical pathways involved in the progression from U atoms to diatoms (UO) and polyatomic molecules (UxOy), employing optical spectroscopy tools and computational modeling. In many studies, laser ablation of U or a U-containing flow reactor are used as a highly resource-efficient, repeatable, tunable, and lab-scale testbed for studying gas-phase oxidation in U plasmas. The spectroscopic analysis of high-temperature gas-phase oxidation of U is challenging due to the congested U spectra, resolution limitations of instrumentation, and the numerous chemical reaction pathways possible. This article focuses on the current understanding and challenges related to studying U plasma chemistry, specifically U gas-phase oxidation and molecular formation, via optical spectroscopy of plasmas and associated computational and spectral modeling. The physical and chemical processes involved in the evolution from U atoms to U oxide molecules to nanoparticles and agglomerates (i.e., debris) are discussed in the context of optical spectroscopic studies. The article concludes by highlighting opportunities for future research efforts based on existing knowledge published in the literature.}, journal={Spectrochimica Acta Part B: Atomic Spectroscopy}, publisher={Elsevier BV}, author={Kautz, Elizabeth J. and Weerakkody, Emily N. and Finko, Mikhail S. and Curreli, Davide and Koroglu, Batikan and Rose, Timothy P. and Weisz, David G. and Crowhurst, Jonathan C. and Radousky, Harry B. and DeMagistris, Michael and et al.}, year={2021}, month={Nov}, pages={106283} }
 @article{kautz_2021, title={Predicting material microstructure evolution via data-driven machine learning}, volume={2}, url={https://doi.org/10.1016/j.patter.2021.100285}, DOI={10.1016/j.patter.2021.100285}, abstractNote={Predicting microstructure evolution can be a formidable challenge, yet it is essential to building microstructure-processing-property relationships. Yang et al. offer a new solution to traditional partial differential equation-based simulations: a data-driven machine learning approach motivated by the practical needs to accelerate the materials design process and deal with incomplete information in the real world of microstructure simulation.}, number={7}, journal={Patterns}, publisher={Elsevier BV}, author={Kautz, Elizabeth J.}, year={2021}, month={Jul}, pages={100285} }
 @article{reehl_kautz_olszta_hopkins_matthews_wang_du_spurgeon_2021, title={Rapid and Flexible Few Shot Learning-Based Classification of Scanning Transmission Electron Microscopy Data}, volume={27}, ISSN={1431-9276 1435-8115}, url={http://dx.doi.org/10.1017/s1431927621005961}, DOI={10.1017/s1431927621005961}, abstractNote={Control of property-defining materials defects for quantum computing and energy storage depends on the ability to precisely probe structure and chemistry at the highest spatial and temporal resolutions. Modern scanning transmission electron microscopy (STEM) is well-suited to this task, having yielded rich insights into defect populations in many systems. However, the dilute nature and complexity of materials defects, coupled with their varied representations in STEM data, makes reliable, accurate, high-throughput statistical defect analysis a significant challenge. Possible analysis approaches include low-level pixel processing, or even the application of machine learning methods for classification and image segmentation. However, the latter requires large sets of labeled training data that are difficult to obtain for many practical materials science studies. Here, we describe the use of an emerging few shot learning capability for rapid and flexible STEM data classification. This approach requires minimal information at the start of the analysis and uses a generally pre-trained encoder network to make inferences on experimental data. Our results show drastic improvements in data annotation costs, reproducibility, and scalability in comparison to neural network training from scratch. We demonstrate how few shot techniques can quickly extract feature maps and global statistics from a variety of STEM data, enabling a new quantitative understanding of defect populations. This research was supported by the Chemical Dynamics Initiative (CDi) Laboratory Directed Research and Development (LDRD) program at Pacific Northwest National Laboratory (PNNL). PNNL is a multi-program the U.S. of by}, number={S1}, journal={Microscopy and Microanalysis}, publisher={Oxford University Press (OUP)}, author={Reehl, Sarah and Kautz, Elizabeth and Olszta, Matthew and Hopkins, Derek and Matthews, Bethany and Wang, Le and Du, Yingge and Spurgeon, Steven}, year={2021}, month={Jul}, pages={1618–1619} }
 @misc{akers_kautz_trevino-gavito_olszta_matthews_wang_du_spurgeon_2021, title={Rapid and Flexible Semantic Segmentation of Electron Microscopy Data Using Few-Shot Machine Learning}, url={http://dx.doi.org/10.21203/rs.3.rs-346102/v1}, DOI={10.21203/rs.3.rs-346102/v1}, abstractNote={Abstract
        Semantic segmentation of key microstructural features in atomic-scale electron microscope images is critical to improved understanding of structure-property relationships in many important materials and chemical systems. However, the present paradigm involves time-intensive manual analysis that is inherently biased, error-prone, and unable to accommodate the large volumes of data produced by modern instrumentation. While more automated approaches have been proposed, many are not robust to a high variety of data, and do not generalize well to diverse microstructural features and material systems. Here, we present a flexible, semi-supervised few-shot machine learning approach for semantic segmentation of scanning transmission electron microscopy images of three oxide material systems: (1) epitaxial heterostructures of SrTiO3 / Ge, (2) La0.8Sr0.2FeO3 thin films, and  (3) MoO3 nanoparticles. We demonstrate that the few-shot learning method is more robust against noise, more reconfigurable, and requires less data than conventional image analysis methods. This approach can enable rapid image classification and microstructural feature mapping needed for emerging high-throughput and autonomous microscope platforms.}, publisher={Research Square Platform LLC}, author={Akers, Sarah and Kautz, Elizabeth and Trevino-Gavito, Andrea and Olszta, Matthew and Matthews, Bethany and Wang, Le and Du, Yingge and Spurgeon, Steven}, year={2021}, month={Mar} }
 @article{akers_kautz_trevino-gavito_olszta_matthews_wang_du_spurgeon_2021, title={Rapid and flexible segmentation of electron microscopy data using few-shot machine learning}, volume={7}, ISSN={2057-3960}, url={http://dx.doi.org/10.1038/s41524-021-00652-z}, DOI={10.1038/s41524-021-00652-z}, abstractNote={AbstractAutomatic segmentation of key microstructural features in atomic-scale electron microscope images is critical to improved understanding of structure–property relationships in many important materials and chemical systems. However, the present paradigm involves time-intensive manual analysis that is inherently biased, error-prone, and unable to accommodate the large volumes of data produced by modern instrumentation. While more automated approaches have been proposed, many are not robust to a high variety of data, and do not generalize well to diverse microstructural features and material systems. Here, we present a flexible, semi-supervised few-shot machine learning approach for segmentation of scanning transmission electron microscopy images of three oxide material systems: (1) epitaxial heterostructures of SrTiO3/Ge, (2) La0.8Sr0.2FeO3 thin films, and (3) MoO3 nanoparticles. We demonstrate that the few-shot learning method is more robust against noise, more reconfigurable, and requires less data than conventional image analysis methods. This approach can enable rapid image classification and microstructural feature mapping needed for emerging high-throughput characterization and autonomous microscope platforms.}, number={1}, journal={npj Computational Materials}, publisher={Springer Science and Business Media LLC}, author={Akers, Sarah and Kautz, Elizabeth and Trevino-Gavito, Andrea and Olszta, Matthew and Matthews, Bethany E. and Wang, Le and Du, Yingge and Spurgeon, Steven R.}, year={2021}, month={Nov} }
 @article{schreiber_kautz_olszta_kruska_gerard_quiambao-tomko_scully_2022, title={Revealing the complexity of high temperature oxide formation in a 38Ni-21Cr-20Fe-13Ru-6Mo-2W (at. %) multi-principal element alloy}, volume={210}, ISSN={1359-6462}, url={http://dx.doi.org/10.1016/j.scriptamat.2021.114419}, DOI={10.1016/j.scriptamat.2021.114419}, abstractNote={The oxide film formed on a corrosion-resistant multi-principal element alloy 38Ni-21Cr-20Fe-13Ru-6Mo-2W (at. %) was characterized via transmission electron microscopy and atom probe tomography. Oxidation in air at 600°C for 1080 minutes resulted in a complex, layered film with multiphase inner and outer oxide scales, and localized recrystallization in the underlying base alloy. The outer oxide scale is dominated by two phases: a Ni-Fe spinel (≈NiFe2O4) and a Ni-rich monoclinic phase (NiMoO4). The inner oxide consists of a near surface Ni-Fe-Cr spinel and RuO2, and semi-continuous Cr2O3 with oxygen-rich Ru-Mo metal inclusions. Local recrystallization and concomitant elemental partitioning in the base alloy was influenced by a high dislocation density in the as-prepared sample surface.}, journal={Scripta Materialia}, publisher={Elsevier BV}, author={Schreiber, Daniel K. and Kautz, Elizabeth J. and Olszta, Matthew J. and Kruska, Karen and Gerard, Angela Y. and Quiambao-Tomko, Kathleen F. and Scully, John R.}, year={2022}, month={Mar}, pages={114419} }
 @misc{harilal_kautz_jones_phillips_2021, title={Simultaneous measurement of optical spectroscopic signatures from ultrafast laser-produced plasmas}, url={http://dx.doi.org/10.1364/cleo_si.2021.sm1e.4}, DOI={10.1364/cleo_si.2021.sm1e.4}, abstractNote={We performed simultaneous measurement of absorption, emission, and laser-induced fluorescence spectroscopic signatures for determining femtosecond laser-produced plasma’s physical properties throughout its lifecycle.}, journal={Conference on Lasers and Electro-Optics}, publisher={Optica Publishing Group}, author={Harilal, Sivanandan S. and Kautz, Elizabeth J. and Jones, R. Jason and Phillips, Mark C.}, year={2021} }
 @misc{kautz_devaraj_senor_harilal_2021, title={Spatio-temporal and spectrally resolved imaging analysis of hydrogen isotopes using ultrafast LIBS}, url={http://dx.doi.org/10.1364/ais.2021.ath4c.5}, DOI={10.1364/ais.2021.ath4c.5}, abstractNote={Spectral imaging and optical time of flight measurements of nanosecond and femtosecond laser- produced Zircaloy-4 plasmas in Ar and He ambient at reduced pressure levels were employed to measure hydrogen isotopes and hydrodynamics of plume species.}, journal={OSA Optical Sensors and Sensing Congress 2021 (AIS, FTS, HISE, SENSORS, ES)}, publisher={Optica Publishing Group}, author={Kautz, Elizabeth J. and Devaraj, Arun and Senor, David J. and Harilal, Sivanandan S.}, year={2021} }
 @article{harilal_kautz_jones_phillips_2021, title={Spectro-temporal comparisons of optical emission, absorption, and laser-induced fluorescence for characterizing ns and fs laser-produced plasmas}, volume={30}, url={https://doi.org/10.1088/1361-6595/abefa5}, DOI={10.1088/1361-6595/abefa5}, abstractNote={Abstract
               We performed simultaneous measurement of absorption, emission, and laser-induced fluorescence spectroscopic signatures for determining nanosecond and femtosecond laser-produced plasma’s (LPP) physical properties throughout its lifecycle. Plasmas are produced by focusing either ∼6 ns, 1064 nm pulses from an Nd:YAG or ∼35 fs, ∼800 nm pulses from a Ti:sapphire laser on an Inconel target that contains Al as a minor alloying addition. A continuous-wave narrowband tunable laser was used for performing absorption and fluorescence spectroscopy while a fast-gated detection system was used for emission spectroscopy. The temporal evolution of emission, fluorescence, and absorbance of Al transitions are compared for both ns and fs LPPs. Time-resolved absorbance was also used for evaluating linewidth, lineshape, temperature, and column-averaged atomic number density at late times of ns and fs plasma evolution. Our results demonstrate that lower and excited-state populations of fs LPPs are short-lived in comparison to those in ns plasmas. The lower state population is observed to reach a maximum value earlier in time for the fs plasma versus the ns plasma, while the kinetic temperature for the ns plasma was higher than for the fs plasma at most times of the plasma evolution.}, number={4}, journal={Plasma Sources Science and Technology}, publisher={IOP Publishing}, author={Harilal, S S and Kautz, E J and Jones, R J and Phillips, M C}, year={2021}, month={Apr}, pages={045007} }
 @article{kautz_senor_harilal_2021, title={The interplay between laser focusing conditions, expansion dynamics, ablation mechanisms, and emission intensity in ultrafast laser-produced plasmas}, url={https://doi.org/10.1063/5.0069732}, DOI={10.1063/5.0069732}, abstractNote={The interplay between ultrafast laser focusing conditions, emission intensity, expansion dynamics, and ablation mechanisms is critical to the detection of light isotopes relevant to nuclear energy, forensics, and geochemistry applications. Here, we study deuterium (2Hα) emission in plasmas generated from femtosecond laser ablation of a Zircaloy-4 target with a deuterium concentration of ≈37 at. %. Changes in emission intensity, plume morphology, crater dimensions, and surface modifications were investigated for varying focusing lens positions, where the laser was focused behind, at, and in front of the target. Spatially resolved optical emission spectroscopy and spectrally integrated plasma imaging were performed to investigate emission spectral features and plume morphology. Laser ablation crater dimensions and morphology were analyzed via optical profilometry and scanning electron microscopy. The 2Hα emission intensity showed significant reduction at the geometrical focal point or when the focal point is in front of the target. For all laser spot sizes, a two-component plume was observed but with different temporal histories. At the best focal point, the plume was spherical. When the laser was focused behind the target, the plume was elongated and propagated to farther distances than for the best focal position. In contrast, when the laser was focused in front of the target, filaments were generated in the beam path, and filament-plasma coupling occurred. By focusing the laser behind the target, the amount of material removal in the laser ablation process can be significantly reduced while still generating a plasma with a sufficient 2Hα emission signal for analysis.}, journal={Journal of Applied Physics}, author={Kautz, Elizabeth J. and Senor, David J. and Harilal, Sivanandan S.}, year={2021}, month={Nov} }
 @article{harilal_kautz_phillips_2021, title={Time-resolved absorption spectroscopic characterization of ultrafast laser-produced plasmas under varying background pressures}, url={https://doi.org/10.1103/PhysRevE.103.013213}, DOI={10.1103/PhysRevE.103.013213}, abstractNote={Time-resolved tunable laser absorption spectroscopy is used to characterize the physical properties of ultrafast laser-produced plasmas. The plasmas were produced from an Inconel target, with ≤0.4wt% Al, using ∼35fs, ∼800nm, ∼5mJ laser pulses at varying Ar background pressures from 1 to 100 Torr. The absorption spectrum of atomic Al is measured with high spectral and temporal resolution when the probe laser is stepped across the selected Al transition at 394.4 nm. Spectral fitting is used to infer linewidths, kinetic temperature, Al column density, and pressure broadening coefficient. The late time physical properties of plasmas are compared for various pressure levels. Our studies highlight that a significant lower state population exists even at early times of ultrafast laser-produced plasma evolution, and lower state population persistence decreases with increasing ambient pressure. We also show that the fundamental optical properties, such as pressure broadening, can be measured using ultrafast laser-produced plasmas combined with laser absorption spectroscopy.}, journal={Physical Review E}, author={Harilal, S. S. and Kautz, E. J. and Phillips, M. C.}, year={2021}, month={Jan} }
 @article{kautz_ma_jana_devaraj_joshi_yener_lewis_2020, title={An image-driven machine learning approach to kinetic modeling of a discontinuous precipitation reaction}, volume={166}, url={https://doi.org/10.1016/j.matchar.2020.110379}, DOI={10.1016/j.matchar.2020.110379}, abstractNote={Microstructure quantification is an essential component of materials science studies, yet, there are no widely applicable, standard methodologies, for image data representation in complex microstructures. Recently, machine learning methods have demonstrated success in image recognition tasks across disciplines, including materials science. In this work, we develop an approach for microstructure quantification for the purpose of kinetic modeling of a discontinuous precipitation reaction. We develop our approach in a case study on a U-Mo alloy which experiences this phase transformation during sub-eutectoid annealing. Prediction of material processing history based on image data (classification), calculation of area fraction of phases present in the micrographs (segmentation), and kinetic modeling from segmentation results were performed as part of this study. Results indicate that features extracted using a convolutional neural network (CNN) represent microstructure image data well, and segmentation via k-means clustering agree well with manually annotated images. Classification accuracy of original and segmented images is both 94% for a 5-class classification problem. Kinetic modeling results are consistent with previously reported data that employed manual thresholding. The image quantification and kinetic modeling approach developed and presented here aims to reduce researcher bias introduced into the characterization process, and allows for efficiently leveraging information in limited, unbalanced image data sets.}, journal={Materials Characterization}, publisher={Elsevier BV}, author={Kautz, Elizabeth and Ma, Wufei and Jana, Saumyadeep and Devaraj, Arun and Joshi, Vineet and Yener, Bülent and Lewis, Daniel}, year={2020}, month={Aug}, pages={110379} }
 @article{gerard_han_mcdonnell_ogle_kautz_schreiber_lu_saal_frankel_scully_2020, title={Aqueous passivation of multi-principal element alloy Ni38Fe20Cr22Mn10Co10: Unexpected high Cr enrichment within the passive film}, volume={198}, ISSN={1359-6454}, url={http://dx.doi.org/10.1016/j.actamat.2020.07.024}, DOI={10.1016/j.actamat.2020.07.024}, abstractNote={The aqueous passivation of a non-equiatomic Ni38Fe20Cr22Mn10Co10 - at.% (Ni40Fe20Cr20Mn10Co10 - wt.%) multi-principal element alloy (MPEA) was investigated in 0.1 M NaCl at pH 4 and compared to a conventional binary Ni76Cr24 – at.% (Ni78Cr22 – wt.%) alloy. The electrochemical behavior and oxide film characteristics were explored utilizing in-situ electrochemical and ex-situ surface-sensitive techniques. The passive film composition, thickness, and elemental valence states, as well as, the fate of each element were studied by in-situ atomic emission spectro-electrochemistry, ex-situ X-ray photoelectron spectroscopy, and atom probe tomography. The Ni38Fe20Cr22Mn10Co10 MPEA demonstrated slightly better corrosion resistance compared to the binary Ni76Cr24, alloy. Passive films on the MPEA contained primarily Cr, and small amounts of Ni, Fe, Co and Mn, while dissolution of Ni, Fe, Co was observed. Ni0 was enriched at the oxide/metal interface while Cr was depleted. Enrichment of Cr in the passive film occurred to a greater extent in the MPEA than for the Ni-Cr binary alloy. Enrichment factors were determined and the origins of enrichment are discussed.}, journal={Acta Materialia}, publisher={Elsevier BV}, author={Gerard, Angela Y. and Han, Junsoo and McDonnell, Stephen J. and Ogle, Kevin and Kautz, Elizabeth J. and Schreiber, Daniel K. and Lu, Pin and Saal, James E. and Frankel, Gerald S. and Scully, John R.}, year={2020}, month={Oct}, pages={121–133} }
 @article{jiang_spurgeon_matthews_battu_china_varga_devaraj_kautz_marcus_reilly_et al._2020, title={Carbonaceous deposits on aluminide coatings in tritium-producing assemblies}, volume={25}, ISSN={2352-1791}, url={http://dx.doi.org/10.1016/j.nme.2020.100797}, DOI={10.1016/j.nme.2020.100797}, abstractNote={Co-deposition of carbon atoms with hydrogen isotopes and hydrogenated carbon radicals and molecules is recognized as the main mechanism for tritium retention in the graphite walls of the previous tokamak fusion devices. Significant tritium retention would be a serious concern for safe and economic long-term operation of future fusion test reactors and fusion energy systems. Similar deposits are observed on the surface of the engineered components in a tritium-producing assembly, known as a Tritium-Producing Burnable Absorber Rod (TPBAR). Characterization of the deposits can help understand the tritium transport, accumulation history and distribution in TPBARs. This study reports our recent results from the carbonaceous deposits formed on an aluminide-coated cladding in the lower plenum of a TPBAR following thermal neutron irradiation. The observed deposits are amorphous in nature, consisting of flakes of interconnected nanoscale features. They contain primarily double-bonded carbon (e.g., alkene) and carbonyl carbon, as well as a minor fraction of aliphatic carbon, all of which are likely tritiated. A similar co-deposition process that occurred in previous fusion devices is responsible for the formation and growth of the carbonaceous deposits.}, journal={Nuclear Materials and Energy}, publisher={Elsevier BV}, author={Jiang, Weilin and Spurgeon, Steven R. and Matthews, Bethany E. and Battu, Anil K. and China, Swarup and Varga, Tamas and Devaraj, Arun and Kautz, Elizabeth J. and Marcus, Matthew A. and Reilly, Dallas D. and et al.}, year={2020}, month={Dec}, pages={100797} }
 @article{kautz_cliff_lach_reilly_devaraj_2021, title={Correlating nanoscale secondary ion mass spectrometry and atom probe tomography analysis of uranium enrichment in metallic nuclear fuel}, url={https://doi.org/10.1039/D0AN01831G}, DOI={10.1039/D0AN01831G}, abstractNote={235U enrichment in a metallic nuclear fuel was measuredviaNanoSIMS and APT, allowing for a direct comparison of enrichment across length scales and resolutions.}, journal={The Analyst}, publisher={Royal Society of Chemistry (RSC)}, author={Kautz, Elizabeth and Cliff, John and Lach, Timothy and Reilly, Dallas and Devaraj, Arun}, year={2021} }
 @article{frank_nene_chen_gwalani_kautz_devaraj_an_mishra_2020, title={Correlating work hardening with co-activation of stacking fault strengthening and transformation in a high entropy alloy using in-situ neutron diffraction}, volume={10}, ISSN={2045-2322}, url={http://dx.doi.org/10.1038/s41598-020-79492-8}, DOI={10.1038/s41598-020-79492-8}, abstractNote={AbstractTransformation induced plasticity (TRIP) leads to enhancements in ductility in low stacking fault energy (SFE) alloys, however to achieve an unconventional increase in strength simultaneously, there must be barriers to dislocation motion. While stacking faults (SFs) contribute to strengthening by impeding dislocation motion, the contribution of SF strengthening to work hardening during deformation is not well understood; as compared to dislocation slip, twinning induced plasticity (TWIP) and TRIP. Thus, we used in-situ neutron diffraction to correlate SF strengthening to work hardening behavior in a low SFE Fe40Mn20Cr15Co20Si5 (at%) high entropy alloy, SFE ~ 6.31 mJ m−2. Cooperative activation of multiple mechanisms was indicated by increases in SF strengthening and γ-f.c.c. → ε-h.c.p. transformation leading to a simultaneous increase in strength and ductility. The present study demonstrates the application of in-situ, neutron or X-ray, diffraction techniques to correlating SF strengthening to work hardening.}, number={1}, journal={Scientific Reports}, publisher={Springer Science and Business Media LLC}, author={Frank, M. and Nene, S. S. and Chen, Y. and Gwalani, B. and Kautz, E. J. and Devaraj, A. and An, K. and Mishra, R. S.}, year={2020}, month={Dec}, pages={22263} }
 @article{kautz_lambeets_perea_gerard_han_scully_saal_schreiber_2021, title={Element redistributions during early stages of oxidation in a Ni38Cr22Fe20Mn10Co10 multi-principal element alloy}, volume={194}, url={https://doi.org/10.1016/j.scriptamat.2020.10.051}, DOI={10.1016/j.scriptamat.2020.10.051}, abstractNote={Element redistributions after initial oxidation of a Ni38Cr22Fe20Mn10Co10 (at.%) multi-principle element alloy at 120 °C and 300 °C is captured via in situ atom probe tomography. All cations contribute to the oxide in both conditions, consisting of a Cr-rich inner oxide and a Fe, Mn, Co and Ni-rich outer oxide. At lower temperature, Ni tends to be trapped at the outer/inner oxide interface, while Ni enriches at the oxide/metal interface at higher temperature in tandem with Cr metal depletion. These observations confirm oxidation of complex alloys involves the formation of metastable, multi-layered oxide films, with a distinct tendency for solute trapping.}, journal={Scripta Materialia}, publisher={Elsevier BV}, author={Kautz, Elizabeth J. and Lambeets, Sten V. and Perea, Daniel E. and Gerard, Angela Y. and Han, Junsoo and Scully, John R. and Saal, James E. and Schreiber, Daniel K.}, year={2021}, month={Mar}, pages={113609} }
 @article{kautz_yeak_bernacki_phillips_harilal_2020, title={Expansion dynamics and chemistry evolution in ultrafast laser filament produced plasmas}, url={https://doi.org/10.1039/D0CP00078G}, DOI={10.1039/D0CP00078G}, abstractNote={2D plume and spectral imaging illustrate expansion dynamics and corresponding chemical evolution of atoms and molecules in filament produced plasmas.}, journal={Physical Chemistry Chemical Physics}, publisher={Royal Society of Chemistry (RSC)}, author={Kautz, Elizabeth J. and Yeak, Jeremy and Bernacki, Bruce E. and Phillips, Mark C. and Harilal, Sivanandan S.}, year={2020} }
 @article{gwalani_olszta_varma_li_soulami_kautz_pathak_rohatgi_sushko_mathaudhu_et al._2020, title={Extreme shear-deformation-induced modification of defect structures and hierarchical microstructure in an Al–Si alloy}, volume={1}, url={https://doi.org/10.1038/s43246-020-00087-x}, DOI={10.1038/s43246-020-00087-x}, abstractNote={AbstractExtreme shear deformation is used for several material processing methods and is unavoidable in many engineering applications in which two surfaces are in relative motion against each other while in physical contact. The mechanistic understanding of the microstructural evolution of multi-phase metallic alloys under extreme shear deformation is still in its infancy. Here, we highlight the influence of shear deformation on the microstructural hierarchy and mechanical properties of a binary as-cast Al-4 at.% Si alloy. Shear-deformation-induced grain refinement, multiscale fragmentation of the eutectic Si-lamellae, and metastable solute saturated phases with distinctive defect structures led to a two-fold increase in the flow stresses determined by micropillar compression testing. These results highlight that shear deformation can achieve non-equilibrium microstructures with enhanced mechanical properties in Al–Si alloys. The experimental and computational insights obtained here are especially crucial for developing predictive models for microstructural evolution of metals under extreme shear deformation.}, number={1}, journal={Communications Materials}, publisher={Springer Science and Business Media LLC}, author={Gwalani, Bharat and Olszta, Matthew and Varma, Soumya and Li, Lei and Soulami, Ayoub and Kautz, Elizabeth and Pathak, Siddhartha and Rohatgi, Aashish and Sushko, Peter V. and Mathaudhu, Suveen and et al.}, year={2020}, month={Nov} }
 @inproceedings{harilal_kautz_bernacki_phillips_skrodzki_burger_murzyn_martin_mitra_bisson_2020, title={Gas-Phase Molecular Formation in Actinide Laser-Produced Plasmas}, url={http://dx.doi.org/10.1109/icops37625.2020.9717872}, DOI={10.1109/icops37625.2020.9717872}, abstractNote={Uranium and plutonium oxidize very rapidly in an oxygen-rich environment like air. Understanding the gas-phase actinide oxide molecular formation through plasma- and thermochemistry is very important for numerous fields including forensic analysis, environmental monitoring, debris analysis in a weapons detonation event, or reactor accident scenario, and actinide nucleation physics. There have been significant recent efforts to understand the chemical progression from U atoms to diatoms (UO) and polyatomic molecules (UxOy).1–3 However, emission analysis of high-temperature gas-phase oxidation of U and Pu and the corresponding plasma chemistry are very complex considering their very congested spectral features. In addition to these, the spectra may contain isotopic shifts and hyperfine structures if the sample is enriched.}, booktitle={2020 IEEE International Conference on Plasma Science (ICOPS)}, publisher={IEEE}, author={Harilal, S. S. and Kautz, E. J. and Bernacki, B. E. and Phillips, M. C. and Skrodzki, I. Jovanovic P. and Burger, M. and Murzyn, C. M. and Martin, J. B. and Mitra, S. S. and Bisson, S. E.}, year={2020}, month={Dec} }
 @article{kautz_devaraj_senor_harilal_2021, title={Hydrogen isotopic analysis of nuclear reactor materials using ultrafast laser-induced breakdown spectroscopy}, url={https://doi.org/10.1364/OE.412351}, DOI={10.1364/OE.412351}, abstractNote={Laser-induced breakdown spectroscopy is a promising method for rapidly measuring hydrogen and its isotopes, critical to a wide range of disciplines (e.g. nuclear energy, hydrogen storage). However, line broadening can hinder the ability to detect finely spaced isotopic shifts. Here, the effects of varying plasma generation conditions (nanosecond versus femtosecond laser ablation) and ambient environments (argon versus helium gas) on spectral features generated from Zircaloy-4 targets with varying hydrogen isotopic compositions were studied. Time-resolved 2D spectral imaging was employed to detail the spatial distribution of species throughout plasma evolution. Results highlight that hydrogen and deuterium isotopic shifts can be measured with minimal spectral broadening in a ∼ 10 Torr helium gas environment using ultrafast laser-produced plasmas.}, journal={Optics Express}, author={Kautz, E. J. and Devaraj, A. and Senor, D. J. and Harilal, S. S.}, year={2021}, month={Feb} }
 @article{ma_kautz_baskaran_chowdhury_joshi_yener_lewis_2020, title={Image-driven discriminative and generative machine learning algorithms for establishing microstructure–processing relationships}, url={https://doi.org/10.1063/5.0013720}, DOI={10.1063/5.0013720}, abstractNote={We investigate the methods of microstructure representation for the purpose of predicting processing condition from microstructure image data. A binary alloy (uranium–molybdenum) that is currently under development as a nuclear fuel was studied for the purpose of developing an improved machine learning approach to image recognition, characterization, and building predictive capabilities linking microstructure to processing conditions. Here, we test different microstructure representations and evaluate model performance based on the F1 score. A F1 score of 95.1% was achieved for distinguishing between micrographs corresponding to ten different thermo-mechanical material processing conditions. We find that our newly developed microstructure representation describes image data well, and the traditional approach of utilizing area fractions of different phases is insufficient for distinguishing between multiple classes using a relatively small, imbalanced original dataset of 272 images. To explore the applicability of generative methods for supplementing such limited datasets, generative adversarial networks were trained to generate artificial microstructure images. Two different generative networks were trained and tested to assess performance. Challenges and best practices associated with applying machine learning to limited microstructure image datasets are also discussed. Our work has implications for quantitative microstructure analysis and development of microstructure–processing relationships in limited datasets typical of metallurgical process design studies.}, journal={Journal of Applied Physics}, author={Ma, W. and Kautz, E. J. and Baskaran, A. and Chowdhury, A. and Joshi, V. and Yener, B. and Lewis, D. J.}, year={2020}, month={Oct} }
 @inproceedings{harilal_kautz_phillips_murzyn_martin_mitra_bisson_2020, title={Laser-Induced Fluorescence Spectroscopic Analysis of U and Pu Plasmas}, url={http://dx.doi.org/10.1109/icops37625.2020.9717826}, DOI={10.1109/icops37625.2020.9717826}, abstractNote={Currently, actinide (eg. U, Pu, etc.) analysis at various facilities has been carried out using inductively-coupled plasma mass spectrometry (ICP-MS), inductively-coupled plasma optical emission spectroscopy (ICP-OES), and thermal ionization spectrometry and all these techniques need extensive, and hence time-consuming, laboratory-based sample preparation. Optical spectroscopic tools such as emission, absorption, and fluorescence have the potential to perform in-field, rapid, and non-contact actinide analysis. Laser-induced breakdown spectroscopy which employs emission spectroscopy of laser-produced plasma was previously used for U plasma analysis including isotopic detection.1 However, the use of emission-based spectroscopic tools for actinide analysis is always challenging considering the extremely congested spectra of all actinides including U and Pu. For example, there exist nearly 100,000 transitions in the UV-VIS spectral range for uranium neutrals and singly ionized species. In addition to these, the emission spectroscopic tools are constrained by instrumental broadening which dictates the available spectral resolution. In this context, laser-induced fluorescence (LIF) and laser-absorption spectroscopy (LAS) are useful tools for obtaining high-resolution spectral features, linewidths, isotopic shifts and hyperfine structures. Although extensive studies have been carried out on optical spectroscopy of U, data on the spectroscopy of Pu is very limited.}, booktitle={2020 IEEE International Conference on Plasma Science (ICOPS)}, publisher={IEEE}, author={Harilal, S. S. and Kautz, E. J. and Phillips, M.C. and Murzyn, C. M. and Martin, J. B. and Mitra, S. S. and Bisson, S. E.}, year={2020}, month={Dec} }
 @article{lambeets_kautz_wirth_orren_devaraj_perea_2020, title={Nanoscale Perspectives of Metal Degradation via In Situ Atom Probe Tomography}, volume={63}, url={https://doi.org/10.1007/s11244-020-01367-z}, DOI={10.1007/s11244-020-01367-z}, abstractNote={AbstractWe report a unique in situ instrument development effort dedicated to studying gas/solid interactions relevant to heterogeneous catalysis and early stages of oxidation of materials via atom probe tomography and microscopy (APM). An in situ reactor cell, similar in concept to other reports, has been developed to expose nanoscale volumes of material to reactive gas environments, in which temperature, pressure, and gas chemistry are well controlled. We demonstrate that the combination of this reactor cell with APM techniques can aid in building a better mechanistic understanding of resultant composition and surface and subsurface structure changes accompanying gas/surface reactions in metal and metal alloy systems through a series of case studies: O2/Rh, O2/Co, and O2/Zircaloy-4. In addition, the basis of a novel operando mode of analysis within an atom probe instrument is also reported. The work presented here supports the implementation of APM techniques dedicated to atomic to near-atomically resolved gas/surface interaction studies of materials broadly relevant to heterogeneous catalysis and oxidation.
}, number={15-18}, journal={Topics in Catalysis}, publisher={Springer Science and Business Media LLC}, author={Lambeets, Sten V. and Kautz, Elizabeth J. and Wirth, Mark G. and Orren, Graham J. and Devaraj, Arun and Perea, Daniel E.}, year={2020}, month={Nov}, pages={1606–1622} }
 @article{kautz_gwalani_lambeets_kovarik_schreiber_perea_senor_liu_battu_tseng_et al._2020, title={Rapid assessment of structural and compositional changes during early stages of zirconium alloy oxidation}, url={https://doi.org/10.1038/s41529-020-00133-6}, DOI={10.1038/s41529-020-00133-6}, abstractNote={AbstractA multimodal chemical imaging approach has been developed and applied to detail the dynamic, atomic-scale changes associated with oxidation of a zirconium alloy (Zircaloy-4). Scanning transmission electron microscopy, a gas-phase reactor chamber attached to an atom probe tomography instrument, and synchrotron-based X-ray absorption near-edge spectroscopy were employed to reveal morphology, composition, crystal, and electronic structure changes that occur during initial stages of oxidation at 300 °C. Oxidation was carried out in 10 mbar O2 gas for short exposure times of 1 and 5 min. A multilayered oxide film with a cubic ZrO adjacent to the oxide/metal interface, a nanoscopic transition region with a graded composition of ZrO2−x (where 0 < x < 1), and tetragonal ZrO2 in the outermost oxide were formed. Partitioning of the major alloying element (tin) to the oxide/metal interface and heterogeneously within the oxide accompanied the development of the layered oxide. Our work provides a rapid, high-throughput approach for detailed characterisation of initial stages of zirconium alloy oxidation at an accelerated time scale, with implications for several other alloy systems.}, journal={npj Materials Degradation}, author={Kautz, Elizabeth J. and Gwalani, Bharat and Lambeets, Sten V. M. and Kovarik, Libor and Schreiber, Daniel K. and Perea, Daniel E. and Senor, David and Liu, Yi-Sheng and Battu, Anil K. and Tseng, Kuo-Pin and et al.}, year={2020}, month={Sep} }
 @article{harilal_murzyn_kautz_edwards_sinkov_bisson_mitra_martin_2021, title={Spectral dynamics and gas-phase oxidation of laser-produced plutonium plasmas}, url={https://doi.org/10.1039/D0JA00416B}, DOI={10.1039/D0JA00416B}, abstractNote={Pu gas-phase oxidation and Pu oxide bands identified with Pu I spectral modeling and time-resolved excitation temperature of Pu plasma.}, journal={Journal of Analytical Atomic Spectrometry}, publisher={Royal Society of Chemistry (RSC)}, author={Harilal, S. S. and Murzyn, C. M. and Kautz, E. J. and Edwards, M. K. and Sinkov, S. I. and Bisson, S. E. and Mitra, S. S. and Martin, J. B.}, year={2021} }
 @article{kautz_yeak_bernacki_phillips_harilal_2020, title={The role of ambient gas confinement, plasma chemistry, and focusing conditions on emission features of femtosecond laser-produced plasmas}, url={https://doi.org/10.1039/D0JA00111B}, DOI={10.1039/D0JA00111B}, abstractNote={Image of the filament ablation with femtosecond laser and filament ablation craters.}, journal={Journal of Analytical Atomic Spectrometry}, publisher={Royal Society of Chemistry (RSC)}, author={Kautz, Elizabeth J. and Yeak, Jeremy and Bernacki, Bruce E. and Phillips, Mark C. and Harilal, Sivanandan S.}, year={2020} }
 @article{kautz_phillips_harilal_2020, title={Unraveling Spatio-Temporal Chemistry Evolution in Laser Ablation Plumes and Its Relation to Initial Plasma Conditions}, volume={92}, url={https://doi.org/10.1021/acs.analchem.0c02477}, DOI={10.1021/acs.analchem.0c02477}, abstractNote={The chemistry evolution in a laser ablation plume depends strongly on its initial physical conditions. In this article, we investigate the impact of plasma generation conditions on the interrelated phenomena of expansion dynamics, plasma chemistry, and physical conditions. Plasmas are produced from a uranium metal target in air using nanosecond, femtosecond, and femtosecond filament-assisted laser ablation. Time-resolved two-dimensional spectral imaging was performed to evaluate the spatio-temporal evolution of atoms, diatoms, polyatomic molecules, and nanoparticles in situ. Emission spectral features reveal that molecular formation occurs at early times in both femtosecond and filament ablation plumes, although with different temporal decay. In contrast, molecular formation is found to occur at much later times in nanosecond plasma evolution. Spectral modeling is used to infer temporal behavior of plasma excitation temperature, and results highlight nanosecond plume temperatures decay rapidly while plumes generated by filament ablation show the slowest decay. We find U atoms and UO molecules co-exist in ultrafast laser produced plasmas even at early times after plasma onset owing to favorable temperatures for molecular formation. Regardless of irradiation conditions, plume emission features showed presence of higher oxides (i.e. UxOy), although with different temporal histories. Our study provides insight into the impact of plasma generation conditions on chemistry evolution in plasmas produced from traditional focused femtosecond, nanosecond, and filament-assisted laser ablation.}, number={20}, journal={Analytical Chemistry}, publisher={American Chemical Society (ACS)}, author={Kautz, Elizabeth J. and Phillips, Mark C. and Harilal, Sivanandan S.}, year={2020}, month={Oct}, pages={13839–13846} }
 @article{kautz_hagen_johns_burkes_2019, title={A machine learning approach to thermal conductivity modeling: A case study on irradiated uranium-molybdenum nuclear fuels}, volume={161}, ISSN={0927-0256}, url={http://dx.doi.org/10.1016/j.commatsci.2019.01.044}, DOI={10.1016/j.commatsci.2019.01.044}, abstractNote={A deep neural network was developed for the purpose of predicting thermal conductivity with a case study performed on neutron irradiated nuclear fuel. Traditional thermal conductivity modeling approaches rely on existing theoretical frameworks that describe known, relevant phenomena that govern the microstructural evolution processes during neutron irradiation (such as recrystallization, and pore size, distribution and morphology). Current empirical modeling approaches, however, do not represent all irradiation test data well. Here, we develop a machine learning approach to thermal conductivity modeling that does not require a priori knowledge of a specific material microstructure and system of interest. Our approach allows researchers to probe dependency of thermal conductivity on a variety of reactor operating and material conditions. The purpose of building such a model is to allow for improved predictive capabilities linking structure-property-processing-performance relationships in the system of interest (here, irradiated nuclear fuel), which could lead to improved experimental test planning and characterization. The uranium-molybdenum system is the fuel system studied in this work, and historic irradiation test data is leveraged for model development. Our model achieved a mean absolute percent error of approximately 4% for the validation data set (when a leave-one-out cross validation approach was applied). Results indicate our model generalizes well to never before seen data, and thus use of deep learning methods for material property predictions from limited, historic irradiation test data is a viable approach. This work is at the frontier of the evolving paradigm in materials science, where machine learning methods are being applied to material property predictions in lieu of limited experimental data fitted to low-dimensionality phenomenological models. The work presented here aims to demonstrate the potential and limitations of machine learning in the field of materials science and material property modeling.}, journal={Computational Materials Science}, publisher={Elsevier BV}, author={Kautz, Elizabeth J. and Hagen, Alexander R. and Johns, Jesse M. and Burkes, Douglas E.}, year={2019}, month={Apr}, pages={107–118} }
 @inproceedings{settle_cleveland_huo_york_farberow_kautz_deavaraj_ramasamy_richards_unocic_et al._2019, title={Atomic Layer Deposition to Extend Catalyst Lifetime for Biobased Adipic Acid Production-Application and Scale-up Considerations}, booktitle={2019 North American Catalysis Society Meeting}, author={Settle, A. and Cleveland, N. and Huo, X. and York, A. and Farberow, C. and Kautz, E. and Deavaraj, A. and Ramasamy, K. and Richards, R. and Unocic, K.A. and et al.}, year={2019} }
 @article{ballor_ikeda_kautz_boehlert_devaraj_2019, title={Composition-Dependent Microstructure-Property Relationships of Fe and Al Modified Ti-12Cr (wt.%)}, volume={71}, ISSN={1047-4838 1543-1851}, url={http://dx.doi.org/10.1007/s11837-019-03467-y}, DOI={10.1007/s11837-019-03467-y}, number={7}, journal={JOM}, publisher={Springer Science and Business Media LLC}, author={Ballor, J. and Ikeda, M. and Kautz, E. J. and Boehlert, C. J. and Devaraj, A.}, year={2019}, month={Apr}, pages={2321–2330} }
 @article{devaraj_matthews_arey_kautz_sevigny_senor_2019, title={Comprehensive Analysis of Hydrogen, Deuterium, Tritium and Isotopic Ratios of Other Light Elements in Neutron Irradiated TPBAR Components}, volume={25}, ISSN={1431-9276 1435-8115}, url={http://dx.doi.org/10.1017/s1431927619002137}, DOI={10.1017/s1431927619002137}, abstractNote={Tritium, a hydrogen isotope of significant importance, is generated by neutron irradiation of Tritium Producing Burnable Absorber Rods (TPBARs), which are specifically designed to produce and capture tritium [1, 2]. A schematic of TPBAR is given in figure 1 (a). Inside each TPBAR there are lithium aluminate pellets, enriched in Li that produces tritium upon neutron irradiation. Tritium is then absorbed by a Zircaloy-4 getter tube that surrounds the LiAlO2 pellet. These components are encapsulated inside a stainless steel cladding which is expected to prevent the diffusion of tritium towards outside. Understanding how various elements in each component gets redistributed under neutron irradiation is a challenging task since it involves quantitatively analyzing changes in distribution of light elements like Li, H isotopes, He, O and other heavy elements. Most traditional characterization methods including electron microscopy and diffraction studies using X-rays do not have sufficient sensitivity or spatial resolution needed for this study, especially when it comes to light elements. Hence in this work we utilized Atom probe tomography to systematically analyze the solute distribution in both as-fabricated and irradiated TPBAR components to obtain a comprehensive understanding of the microstructural evolution under irradiation.}, number={S2}, journal={Microscopy and Microanalysis}, publisher={Oxford University Press (OUP)}, author={Devaraj, Arun and Matthews, Bethany and Arey, Bruce and Kautz, Elizabeth and Sevigny, Gary and Senor, David}, year={2019}, month={Aug}, pages={280–281} }
 @article{kautz_lambeets_gwalani_kovarik_perea_devaraj_2019, title={Direct Observation of Zirconium Alloy Oxidation at the Nanoscale}, volume={25}, ISSN={1431-9276 1435-8115}, url={http://dx.doi.org/10.1017/s1431927619002320}, DOI={10.1017/s1431927619002320}, abstractNote={Zirconium (Zr)-based alloys are commonly used in the nuclear industry for a variety of applications, such as nuclear reactor fuel cladding in pressurized water reactors, and as a hydrogen isotope absorbing material in tritium producing burnable absorber rods (TPBARs). Zr alloys are widely used in such applications due to their favorable mechanical behavior (e.g. yield strength, fracture toughness, creep, etc.), corrosion resistance, and low thermal neutron cross-section [1]. Despite these many desirable properties, corrosion of Zr alloys can limit component lifetime. A better understanding of oxide formation mechanisms and kinetics could thus enable improved alloy design and predictive capabilities related to fuel assembly degradation, such in a reactor operating environment, in spent fuel storage pools, or during an accident scenario (e.g. Fukushima-Dai Ichi, Three Mile Island, and Chernobyl).}, number={S2}, journal={Microscopy and Microanalysis}, publisher={Oxford University Press (OUP)}, author={Kautz, Elizabeth and Lambeets, Sten and Gwalani, Bharat and Kovarik, Libor and Perea, Daniel and Devaraj, Arun}, year={2019}, month={Aug}, pages={318–319} }
 @article{settle_cleveland_farberow_conklin_huo_dameron_tracy_sarkar_kautz_devaraj_et al._2019, title={Enhanced Catalyst Durability for Bio-Based Adipic Acid Production by Atomic Layer Deposition}, volume={3}, ISSN={2542-4351}, url={http://dx.doi.org/10.1016/j.joule.2019.06.022}, DOI={10.1016/j.joule.2019.06.022}, abstractNote={Atomic layer deposition (ALD) improves the durability of metal catalysts using nanoscale metal oxide coatings. However, targeted coating strategies and economic models are lacking for process-specific deactivation challenges that account for implications at scale. Herein, we apply Al2O3 ALD to Pd/TiO2 to increase durability during hydrogenation of muconic acid, a bio-based platform chemical, to adipic acid. Initial coating development and characterization are performed on the milligram scale using stop-flow ALD. Subsequently, ALD coating scale is increased by 3 orders of magnitude using fluidized bed ALD. Activity, leaching resistance, and thermal stability are evaluated at each synthesis scale. ALD-coated catalysts retain up to 2-fold greater muconic acid hydrogenation activity and undergo significantly less physical restructuring than uncoated Pd/TiO2 after high-temperature treatments, while reducing Pd leaching by over 4-fold. Techno-economic analysis for an adipic acid biorefinery supports increased ALD material costs through catalyst lifetime extension, underscoring the potential viability of this technology.}, number={9}, journal={Joule}, publisher={Elsevier BV}, author={Settle, Amy E. and Cleveland, Nicholas S. and Farberow, Carrie A. and Conklin, Davis R. and Huo, Xiangchen and Dameron, Arrelaine A. and Tracy, Ryon W. and Sarkar, Reuben and Kautz, Elizabeth J. and Devaraj, Arun and et al.}, year={2019}, month={Sep}, pages={2219–2240} }
 @book{jana_schemer-kohrn_overman_sweet_kautz_lavender_joshi_2019, title={Eutectoid Transformation in U10Mo Alloy: Effect of Deformation History and Homogenization Heat Treatment}, url={http://dx.doi.org/10.2172/1503687}, DOI={10.2172/1503687}, abstractNote={In the United States, uranium 10 wt.% molybdenum (U10Mo) alloy has been selected as the nuclear fuel that will be used when transitioning research reactors and radioisotope production facilities from highly enriched uranium (>85% 235U) fuel to low-enriched uranium (<20% 235U) fuel. The fabrication steps for producing U10Mo fuel foil involve multiple hot-rolling/cold-rolling/intermediate annealing steps. The U10Mo alloy, which can retain the desirable high-temperature body-centered cubic γ-U (A2) structure at room temperature as a metastable phase for optimum in-reactor performance, goes through a eutectoid reaction below ~560°C and forms a-U as a reaction product, which is highly undesirable. Because the fabrication steps are carried out in the temperature range of 500 to 700°C, it is critical to understand the eutectoid reaction kinetics as a function of rolling/annealing steps. In this study, we determined the eutectoid transformation behavior of various rolled/annealed U10Mo coupons at 450, 500, and 525°C. The results show that the highest degree of phase transformation occurs when the U10Mo billet is rolled down from the as-cast condition without any prior homogenization treatment. Further, we observed that mechanical deformation (in the form of hot-rolling/cold-rolling) leads to increased eutectoid transformation compared to the billets that were not deformed.}, institution={Office of Scientific and Technical Information (OSTI)}, author={Jana, Saumyadeep and Schemer-Kohrn, Alan L. and Overman, Nicole R. and Sweet, Lucas E. and Kautz, Elizabeth J. and Lavender, Curt A. and Joshi, Vineet V.}, year={2019}, month={Jan} }
 @article{perea_schreiber_devaraj_reilly_lambeets_kautz_lach_wirth_evans_2019, title={Exploring New Science Domains with Atom Probe Tomography Enabled by an Environmental Transfer Hub}, volume={25}, ISSN={1431-9276 1435-8115}, url={http://dx.doi.org/10.1017/s1431927619002113}, DOI={10.1017/s1431927619002113}, abstractNote={Daniel E. Perea1, Daniel K. Schreiber2, Arun Devaraj3, Dallas D. Reilly4, Sten V. Lambeets1, Elizabeth J. Kautz4, Timothy G. Lach2, Mark G. Wirth1, James E. Evans1 1. Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA USA 2. Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, WA USA 3. Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA USA 4. National Security Directorate; Pacific Northwest National Laboratory, Richland, WA USA * Corresponding author: daniel.perea@pnnl.gov}, number={S2}, journal={Microscopy and Microanalysis}, publisher={Oxford University Press (OUP)}, author={Perea, Daniel E. and Schreiber, Daniel K. and Devaraj, Arun and Reilly, Dallas D. and Lambeets, Sten V. and Kautz, Elizabeth J. and Lach, Timothy G. and Wirth, Mark G. and Evans, James E.}, year={2019}, month={Aug}, pages={276–277} }
 @article{ballor_kautz_gwalani_boehlert_devaraj_2019, title={Influence of Composition and Structure on Measured H Concentration in beta-Ti Alloys via Atom Probe Tomography}, volume={25}, ISSN={1431-9276 1435-8115}, url={http://dx.doi.org/10.1017/s1431927619013448}, DOI={10.1017/s1431927619013448}, number={S2}, journal={Microscopy and Microanalysis}, publisher={Oxford University Press (OUP)}, author={Ballor, JoAnn and Kautz, Elizabeth and Gwalani, Bharat and Boehlert, Carl and Devaraj, Arun}, year={2019}, month={Aug}, pages={2542–2543} }
 @article{gwalani_kautz_kaspar_kovarik_joshi_mathaudhu_rohatgi_sushko_devaraj_2019, title={Multimodal Atomic Scale Characterization of Structural and Compositional Changes During Shear Deformation of Materials}, volume={25}, ISSN={1431-9276 1435-8115}, url={http://dx.doi.org/10.1017/s143192761901328x}, DOI={10.1017/s143192761901328x}, abstractNote={Bharat Gwalani, Elizabeth J. Kautz, Tiffany Kaspar, Libor Kovarik, Vineet V. Joshi, Suveen Mathaudhu , Aashish Rohatgi, Peter Sushko and Arun Devaraj Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA National Security Directorate, Pacific Northwest National Laboratory, Richland, WA Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA Energy and Environment Directorate, Pacific Northwest National Laboratory Richland USA Mechanical Engineering and Material Science and Engineering, University of California Riverside, CA *Corresponding author: arun.devaraj@pnnl.gov}, number={S2}, journal={Microscopy and Microanalysis}, publisher={Oxford University Press (OUP)}, author={Gwalani, Bharat and Kautz, Elizabeth J. and Kaspar, Tiffany and Kovarik, Libor and Joshi, Vineet V. and Mathaudhu, Suveen and Rohatgi, Aashish and Sushko, Peter and Devaraj, Arun}, year={2019}, month={Aug}, pages={2510–2511} }
 @article{kautz_burkes_joshi_lavender_devaraj_2019, title={Nanoscale Spatially Resolved Mapping of Uranium Enrichment}, volume={9}, ISSN={2045-2322}, url={http://dx.doi.org/10.1038/s41598-019-48479-5}, DOI={10.1038/s41598-019-48479-5}, abstractNote={AbstractSpatially resolved analysis of uranium (U) isotopes in small volumes of actinide-bearing materials is critical for a variety of technical disciplines, including earth and planetary sciences, environmental monitoring, bioremediation, and the nuclear fuel cycle. However, achieving subnanometer-scale spatial resolution for such isotopic analysis is currently a challenge. By using atom probe tomography—a three-dimensional nanoscale characterisation technique—we demonstrate unprecedented nanoscale mapping of U isotopic enrichment with high sensitivity across various microstructural interfaces within small volumes (~100 nm3) of depleted and low-enriched U alloyed with 10 wt% molybdenum that has different nominal enrichments of 0.20 and 19.75% 235U, respectively. We map enrichment in various morphologies of a U carbide phase, the adjacent γ-UMo matrix, and across interfaces (e.g., carbide/matrix, grain boundary). Results indicate the U carbides were formed during casting, rather than retained from either highly enriched or depleted U feedstock materials. The approach presented here can be applied to study nanoscale variations of isotopic abundances in the broad class of actinide-bearing materials, providing unique insights into their origins and thermomechanical processing routes.}, number={1}, journal={Scientific Reports}, publisher={Springer Science and Business Media LLC}, author={Kautz, Elizabeth and Burkes, Douglas and Joshi, Vineet and Lavender, Curt and Devaraj, Arun}, year={2019}, month={Aug} }
 @article{kautz_lach_reilly_joshi_lavender_devaraj_2019, title={Nanoscale Spatially Resolved Mapping of Uranium Enrichment in Actinide-Bearing Materials}, volume={25}, ISSN={1431-9276 1435-8115}, url={http://dx.doi.org/10.1017/s1431927619013321}, DOI={10.1017/s1431927619013321}, abstractNote={Spatially resolved analysis of uranium isotopes in small volumes of actinide-bearing materials is critical for a variety of technical disciplines, including earth and planetary sciences, environmental monitoring, bioremediation, and the nuclear fuel cycle. However, achieving sub-nanometer scale spatial resolution for such isotopic analysis is currently a challenge. By using atom probe tomography, a three dimensional nanoscale characterization technique, we demonstrate unprecidented nanoscale mapping of uranium isotopic enrichment with high sensitivity across various microstructural interfaces within small volumes (100 nm3) of depleted and low enriched uranium alloyed with 10 wt % molybdenum with different nominal enrichments of 0.20 and 19.75% 235U respectively. The approach presented here can be applied to study nanoscale variations of isotopic abundances in the broad class of actinide-bearing materials, providing unique insights into their origin and thermo-mechanical processing routes.}, number={S2}, journal={Microscopy and Microanalysis}, publisher={Oxford University Press (OUP)}, author={Kautz, Elizabeth and Lach, Timothy and Reilly, Dallas and Joshi, Vineet and Lavender, Curt and Devaraj, Arun}, year={2019}, month={Aug}, pages={2518–2519} }
 @article{harilal_kautz_bernacki_phillips_skrodzki_burger_jovanovic_2019, title={Physical conditions for UO formation in laser-produced uranium plumes}, volume={21}, url={https://doi.org/10.1039/C9CP02250C}, DOI={10.1039/C9CP02250C}, abstractNote={The complex interplay between plume hydrodynamics and chemistry impacts physical conditions leading to UO molecular formation in laser-plasmas.}, number={29}, journal={Physical Chemistry Chemical Physics}, publisher={Royal Society of Chemistry (RSC)}, author={Harilal, S. S. and Kautz, E. J. and Bernacki, B. E. and Phillips, M. C. and Skrodzki, P. J. and Burger, M. and Jovanovic, I.}, year={2019}, pages={16161–16169} }
 @article{kautz_skrodzki_burger_bernacki_jovanovic_phillips_harilal_2019, title={Time-resolved imaging of atoms and molecules in laser-produced uranium plasmas}, volume={34}, url={https://doi.org/10.1039/C9JA00228F}, DOI={10.1039/C9JA00228F}, abstractNote={Spatial temporal contours of atoms and molecules in uranium plasmas reveal complex plasma–chemical interaction between plume and oxygen-containing ambient gas.}, number={11}, journal={Journal of Analytical Atomic Spectrometry}, publisher={Royal Society of Chemistry (RSC)}, author={Kautz, E. J. and Skrodzki, P. J. and Burger, M. and Bernacki, B. E. and Jovanovic, I. and Phillips, M. C. and Harilal, S. S.}, year={2019}, pages={2236–2243} }
 @inproceedings{vardon_settle_cleveland_huo_york_devaraj_kautz_ramasamy_beckham_griffin_et al._2018, place={Washington, DC}, title={Atomic layer deposition with Al2O3 for enhanced Pd/TiO2 stability during biobased adipic acid production}, volume={256}, booktitle={Abstracts of Papers of the American Chemical Society}, publisher={American Chemical Society}, author={Vardon, D. and Settle, A. and Cleveland, N. and Huo, X. and York, A. and Devaraj, A. and Kautz, E. and Ramasamy, K. and Beckham, G. and Griffin, M. and et al.}, year={2018} }
 @article{devaraj_kovarik_kautz_arey_jana_lavender_joshi_2018, title={Grain boundary engineering to control the discontinuous precipitation in multicomponent U10Mo alloy}, volume={151}, ISSN={1359-6454}, url={http://dx.doi.org/10.1016/j.actamat.2018.03.039}, DOI={10.1016/j.actamat.2018.03.039}, abstractNote={We demonstrate here that locally stabilized structure and compositional segregation at grain boundaries in a complex multicomponent alloy can be modified using high temperature homogenization treatment to influence the kinetics of phase transformations initiating from grain boundaries during subsequent low temperature annealing. Using aberration-corrected scanning transmission electron microscopy and atom probe tomography of a model multicomponent metallic alloy —uranium-10 wt% molybdenum (U-10Mo) a nuclear fuel, that is highly relevant to worldwide nuclear non-proliferation efforts, we demonstrate the ability to change the structure and compositional segregation at grain boundary, which then controls the subsequent discontinuous precipitation kinetics during sub-eutectoid annealing. A change in grain boundary from one characterized by segregation of Mo and impurities at grain boundary to a phase boundary with a distinct U2MoSi2C wetting phase precipitates introducing Ni and Al rich interphase complexions caused a pronounced reduction in area fraction of subsequent discontinuous precipitation. The broader implication of this work is in highlighting the role of grain boundary structure and composition in metallic alloys on dictating the fate of grain boundary initiated phase transformations like discontinuous precipitation or cellular transformation. This work highlights a new pathway to tune the grain boundary structure and composition to tailor the final microstructure of multicomponent metallic alloys.}, journal={Acta Materialia}, publisher={Elsevier BV}, author={Devaraj, Arun and Kovarik, Libor and Kautz, Elizabeth and Arey, Bruce and Jana, Saumyadeep and Lavender, Curt and Joshi, Vineet}, year={2018}, month={Jun}, pages={181–190} }
 @article{devaraj_kautz_kovarik_jana_overman_lavender_joshi_2018, title={Phase transformation of metastable discontinuous precipitation products to equilibrium phases in U10Mo alloys}, volume={156}, ISSN={1359-6462}, url={http://dx.doi.org/10.1016/j.scriptamat.2018.07.010}, DOI={10.1016/j.scriptamat.2018.07.010}, abstractNote={The discontinuous precipitation (DP) mechanism is prevalent in over 80 alloy systems. We report a new type of DP occurring along prior γ-UMo grain boundaries of an alloy of uranium with 10 wt% molybdenum (U10Mo) during annealing at 500 °C, forming alternate lamellae of Mo-enriched γ-UMo and α-U. During prolonged annealing, the metastable Mo-enriched γ-UMo lamellae gradually transform into a composite mixture of equilibrium γ′-U2Mo embedded in Mo-depleted γ-UMo. Using high resolution scanning transmission electron microscopy and atom probe tomography, a comprehensive description of the structural and compositional changes of the metastable lamellar DP product to near-equilibrium phases is provided.}, journal={Scripta Materialia}, publisher={Elsevier BV}, author={Devaraj, Arun and Kautz, Elizabeth and Kovarik, Libor and Jana, Saumyadeep and Overman, Nicole and Lavender, Curt and Joshi, Vineet V.}, year={2018}, month={Nov}, pages={70–74} }
 @book{kautz_jana_devaraj_lavender_sweet_joshi_2017, title={Detecting the Extent of Cellular Decomposition after Sub-Eutectoid Annealing in Rolled UMo Foils}, url={http://dx.doi.org/10.2172/1400352}, DOI={10.2172/1400352}, abstractNote={This report presents an automated image processing approach to quantifying microstructure image data, specifically the extent of eutectoid (cellular) decomposition in rolled U-10Mo foils. An image processing approach is used here to be able to quantitatively describe microstructure image data in order to relate microstructure to processing parameters (time, temperature, deformation).}, institution={Office of Scientific and Technical Information (OSTI)}, author={Kautz, Elizabeth J. and Jana, Saumyadeep and Devaraj, Arun and Lavender, Curt A. and Sweet, Lucas E. and Joshi, Vineet V.}, year={2017}, month={Jul} }
 @book{kautz_devaraj_kovarik_lavender_joshi_2017, title={Effect of Silicon in U-10Mo Alloy}, url={http://dx.doi.org/10.2172/1400353}, DOI={10.2172/1400353}, abstractNote={This document details a method for evaluating the effect of silicon impurity content on U-10Mo alloys. Silicon concentration in U-10Mo alloys has been shown to impact the following: volume fraction of precipitate phases, effective density of the final alloy, and 235-U enrichment in the gamma-UMo matrix. This report presents a model for calculating these quantities as a function of Silicon concentration, which along with fuel foil characterization data, will serve as a reference for quality control of the U-10Mo final alloy Si content. Additionally, detailed characterization using scanning electron microscope imaging, transmission electron microscope diffraction, and atom probe tomography showed that Silicon impurities present in U-10Mo alloys form a Si-rich precipitate phase.}, institution={Office of Scientific and Technical Information (OSTI)}, author={Kautz, Elizabeth J. and Devaraj, Arun and Kovarik, Libor and Lavender, Curt A. and Joshi, Vineet V.}, year={2017}, month={Aug} }
 @article{chowdhury_kautz_yener_lewis_2016, title={Image driven machine learning methods for microstructure recognition}, volume={123}, ISSN={0927-0256}, url={http://dx.doi.org/10.1016/j.commatsci.2016.05.034}, DOI={10.1016/j.commatsci.2016.05.034}, abstractNote={Computer vision and machine learning methods were applied to the challenge of automatic microstructure recognition. Here, a case study on dendritic morphologies was performed. Two classification tasks were completed, and involved distinguishing between micrographs that depict dendritic morphologies from those that do not contain this particular microstructural feature (Task 1), and from those micrographs identified as depicting dendrites, different cross-sectional views (longitudinal or transverse) were identified (Task 2). Data sets were comprised of images taken over a range of magnifications, from materials with different compositions and varying orientations of microstructural features. Feature extraction and dimensionality reduction were performed prior to training machine learning algorithms to classify microstructural image data. Visual bag of words, texture and shape statistics, and pre-trained convolutional neural networks (deep learning algorithms) were used for feature extraction. Classification was then performed using support vector machine, voting, nearest neighbors, and random forest models. For each model, classification was completed using full (original size) and reduced feature vectors for each feature extraction method tested. Performance comparisons were done to evaluate all possible combinations of feature extraction, selection, and classifiers for the task of micrograph classification. Results demonstrate that pre-trained neural networks represent microstructure image data well, and when used for feature extraction yield the highest classification accuracies for the majority of classifier and feature selection methods tested. Thus, deep learning algorithms can successfully be applied to micrograph recognition tasks. Maximum classification accuracies of 91.85 ± 4.25% and 97.37 ± 3.33% for Tasks 1 and 2 respectively, were achieved. This work is a broad investigation of computer vision and machine learning methods that acts as a step towards applying these established methods to more sophisticated materials recognition or characterization tasks. The approach presented here could offer improvements over established stereological measurements by removing the requirement of expert knowledge (bias) for interpretation of image data prior to characterization.}, journal={Computational Materials Science}, publisher={Elsevier BV}, author={Chowdhury, Aritra and Kautz, Elizabeth and Yener, Bülent and Lewis, Daniel}, year={2016}, month={Oct}, pages={176–187} }