Mohamed Elbakhshwan

• Researcher at University of Wisconsin–Madison

Enhancement of the diffusion bonding process for the development of compact heat exchangers (CHXs) provides an energy efficient solution for high-temperature applications in advanced nuclear reactors and other technologies. However, available information is limited concerning the diffusion bonding (and manufacturing) of CHXs in high temperature app...

Silicon carbide (SiC) formed through pyrolysis of preceramic polymers loaded with SiC particles has gained significant attention for applications such as coatings, composite matrix modifications, and most importantly additive manufacturing. This work presents combined synchrotron XRD, Raman spectroscopy, scanning electron microscopy, nano-indentati...

This study focuses on the time dependent performance of the corrosion resistance of IN625, H230 and 740H alloys in the solar salt (60 wt% NaNO3, 40 wt% KNO3, at 600 °C) for up to 4000 h. Alloy IN625 showed the lowest mass change with parabolic oxidation kinetics that tends to stabilize with exposure time. Both 740H and H230 alloys deviated from the...

Two CrFeMnNi face-centered cubic complex concentrated solid-solution alloys (CSA) have been evaluated for phase stability, mechanical properties, and radiation damage effects from heavy ions. Cr18Fe27Mn27Ni28 and Cr15Fe35Mn15Ni35 were predicted by thermodynamic calculations to phase separate and maintain a single phase at 700°C, respectively. Aging...

The molten salt-cooled reactor concept has garnered significant interest and one of the current challenges limiting the deployment of these reactor concepts is the complex corrosion phenomenon observed in molten salt environments. One of these phenomena is activity gradient mass transport, which has been shown to affect dissimilar materials submerg...

The use of supercritical carbon dioxide (sCO2) as a working fluid is garnering interest in next generation power production systems due to the possibility of increased operational efficiencies and lower associated costs. Its implementation requires alloys with excellent high temperature strength and corrosion resistance, which makes Haynes 282® (H2...

Oxidation kinetics and scale formation were examined in 21-2 N Stainless Steel alloys in a CO2 environment at 700 °C. Several characterization techniques were used to identify the morphology, crystallographic structure, and chemical composition of the oxide scale formation during exposures up to 1925 hours. High manganese content played an importan...

Description Featuring 37 peer-reviewed and award-winning papers from industry experts that were presented at this 2019 symposium held in Manchester, United Kingdom. Topics covered include Sponsored by ASTM International Committee B10 on Reactive and Refractory Metals and Alloys and its subcommittee Zirconium and Hafnium.

Several advanced nuclear reactor designs promise efficiency and safety improvements over the current reactor fleet but are limited by the current set of ASME code-qualified materials. Novel alloys including high-entropy alloys (HEAs), and more broadly compositionally complex alloys (CCAs), have shown promising irradiation-tolerance. However, the va...

Wellbore cement is subjected to a number of mechanical, thermal and chemical stress regimes over its lifetime. Therefore, next-generation wellbore cement formulations need to be evaluated in conditions relevant to these environments. In this work, we investigate the mechanism of the alteration of a novel self-healing polymer-cement composite after...

Understanding microstructural and strain evolutions induced by noble gas production in the nuclear fuel matrix or plasma-facing materials is crucial for designing next generation nuclear reactors, as they are responsible for volumetric swelling and catastrophic failure. We describe a multimodal approach combining synchrotron-based nanoscale X-ray i...

Compact heat exchangers have high compactness and efficiency, which is achieved by joining a stack of chemically etched channeled plates through diffusion bonding. In the diffusion bonding process, compressive stress is applied on plates at elevated temperatures for a specified period. These conditions lead to atomic diffusion, which results in the...

This study characterizes the microstructural evolution of single-phase complex concentrated solid-solution alloy (CSA) compositions under heavy ion irradiation with the goal of evaluating mechanisms for CSA radiation tolerance in advanced fission systems. Three such alloys, Cr18Fe27Mn27Ni28, Cr15Fe35Mn15Ni35, and equimolar NbTaTiV, along with refer...

Mass transport of corrosion products between Ni-201 test samples and 316L capsules in a 500-hour FLiNaK corrosion experiment has been investigated. In one experiment, the capsule and samples were electrically connected for galvanic coupling, while in the other they were electrically isolated using boron-nitride. Post-corrosion characterization of N...

A 1000 -h corrosion experiment of 316H stainless steel at 700 °C investigated the role of metal fluoride impurities CrF2 and FeF2 in LiF-BeF2 (66-34 mole %) (FLiBe) salt. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) demonstrated the ability to measure changes in the concentration of these fluorides in FLiBe salt. Cyclic voltam...

This study investigates the effectiveness of Cu as a corrosion barrier in supercritical carbon dioxide (s−CO2) by coating 316 stainless steel (316) with various thicknesses of Cu. 316 exposed to s−CO2 with 50 ppm CO showed a reduction in oxidation corresponding to the thickness of its Cu barrier coating. Additionally, a continuous Cu layer between...

The corrosion behavior of the FCC Cr18Mn27Fe27.5Ni27.5 high entropy alloy (HEA) after exposure to molten FLiBe salt at 700 °C for 1000 hours, has been investigated. Results show that the HEA lost a higher mass compared to the reference 316 H stainless steel due to the dissolution of Mn into the molten salt. The loss of Mn from the alloy appeared to...

High-entropy alloys (HEAs) are a class of alloys that can exhibit promising properties including enhanced irradiation resistance, high-temperature strength, and corrosion resistance. However, they exist in a relatively unexplored region of quasi-limitless composition space. Thus, to enable the development of promising compositionally complex alloys...

The effect of UV irradiation on the oxidized zirconium surface during high temperature water corrosion was investigated in both static and flowing conditions. Iron oxide deposits were found to form only on the UV irradiated surfaces. The formation of these deposits resulted from the UV illumination, which induces photo-electrochemical processes at...

The stability of intermetallic second-phase particles (SPPs) in coated Zircaloy-2 was studied in 700 °C steam environments up to 20 hours. Hydrogen generated from high-temperature steam oxidation of uncoated Zr-induced δ-hydrides formation in the Zircaloy matrix. Synchrotron XRD demonstrated that longer exposure times increased hydride peak intensi...

To isolate injection and production zones from overlying formations and aquifers during geothermal operations, cement is placed in the annulus between well casing and the formation. However, wellbore cement eventually undergoes fractures due to chemical and physical stress with the resulting time and cost intensive production shutdowns and repairs....

The in situ response of stoichiometric and non-stoichiometric uranium dioxide during flash sintering is examined using high energy X-ray diffraction. Our results show that the onset of flash is driven by an increase in temperature and controlled by the applied field with no evidence of an accumulation of defects. The incubation time, that is the ti...

Three methods were used to measure the mechanical properties of \({\text{U}}_{3}{\text{Si}}\), \({\text{U}}_3{\text{Si}}_{2}\), and USi. Quasi-static and continuous stiffness measurement nanoindentation were used to determine hardness and Young’s modulus, and microindentation was used to evaluate the bulk hardness. Hardness and Young’s modulus of t...

The effects of temperature changes on the particle orientation of a consolidated kaolin are studied using XRD experiments. Two sets of equipment were utilized in this study: a benchtop equipment, and a synchrotron beamline at the National Synchrotron Light Source II (NSLS-II) at Brookhaven National Laboratory. The kaolin specimens tested in the ben...

Alloys of iron-chromium-nickel are being explored as alternative cladding materials to improve safety margins under severe accident conditions. Our research focuses on non-destructively investigating the oxidation behavior of the FeCrNi alloy “Alloy 33” using synchrotron-based methods The evolution and structure of oxide layer formed in steam envir...

Uranium dioxide thin films were deposited on single crystal TiO2, Al2O3, YSZ, ZnO and NdGaO3 substrates to optimize conditions for the growth of high quality single crystal films. X-ray diffraction results show that all the films have one growth direction and well defined peaks in the specular scans with the expected symmetry for each growth orient...

The mechanical response of UO2 to irradiation is becoming increasingly important due to the shift to higher burn-up rates in the next generation of nuclear reactors. In the current study, thin films of UO2 were deposited on YSZ substrates using reactive-gas magnetron sputtering. Nanoindentation was used to measure the mechanical properties of the a...

A new in situ sample environment has been designed and developed to study the interfacial interactions of nuclear cladding alloys with high temperature steam. The sample environment is particularly optimized for synchrotron X-ray diffraction studies for in situ structural analysis. The sample environment is highly corrosion resistant and can be rea...

AlBeMet 162 (Materion Co., formerly Brush Wellman) has been irradiated with 145 MeV protons up to 1.2 × 1020 cm−2 fluence, with irradiation temperatures in the range of 100–220 °C. Macroscopic post-irradiation evaluation on the evolution of mechanical and thermal properties was integrated with a comprehensive X-ray- diffraction study using high-ene...

Beryllium, due to its excellent neutron multiplication and moderation properties, in conjunction with its good thermal properties, is under consideration for use as plasma facing material in fusion reactors and as a very effective neutron reflector in fission reactors. While it is characterized by unique combination of structural, chemical, atomic...

S-200F grade beryllium has been irradiated with 160 MeV protons up to 0.6 1020 cm−2 fluence and irradiation temperatures in the range of 100-200 °C. To address the effect of proton irradiation on dimensional stability, an important parameter in its consideration in fusion reactor applications, and to simulate high temperature irradiation conditions...

The microstructure and valence states of three single crystal thin film systems, UO2 on (11¯02) r-plane sapphire, UO2 on (001) yttria-stabilized zirconia, and U3O8 on (11¯02) r-plane sapphire, grown via reactive-gas magnetron sputtering are analyzed primarily with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet phot...