High-energy X-ray Research Articles

Ultrahigh-efficiency X-ray energy dissipation enabled by the integration of core–shell photon nanotraps and hierarchical natural leather

The widespread application of high-energy X-ray radiation has prompted improvements in the performance of radiation-protection materials. Currently, achieving enhanced X-ray shielding efficiency and minimized surficial photon scattering remains challenging when using traditional strategies. In this study, an ultrahigh-efficiency X-ray energy absorption strategy and mechanism are proposed by integrating Bi@Gd core–shell photon nanotraps into the hierarchical fibrous network of natural leather (Bi@Gd/NL), and the surficial-energy-transfer energy-attenuation mechanism of the traditional strategy was successfully transformed into internal-energy-dissipation. The proposed strategy could induce high-energy photons into a porous structure composed of hierarchical microfibers and nanofibers to reduce surface-scattered secondary radiation, and the well-assembled high-atomic-number core–shell nanotraps can trap photons within the structure and facilitate collisions and subsequent internal energy dissipation to improve the shielding capabilities. Our analysis shows that Bi@Gd/NL with 1.40 mmol cm−3 Bi and 0.11 mmol cm−3 Gd exhibits superior shielding performance against X-rays, comparable to that of a 0.25-mm Pb plate. More than 99.95 % photon energy is dissipated within the nanotraps, and the surficial scattering of photon is considerably lower than that of materials fabricated using the traditional strategy, indicating that the ionizing radiation hazards are successfully suppressed. Simultaneously, the developed materials demonstrate exceptional wearability, with a density of only 1/10 that of Pb, as well as outstanding flexibility, physiomechanical strength, and irradiation stability. This proposed strategy and mechanism provide important guidance and insights on the development of novel absorption-type shielding materials for protecting ionizing radiation-related individuals and environments.

Methodology for shielding design and evaluation for container scanners.

There has been an increase in the use of high energy photon beam for container scanners in many countries for multi purposes such as detecting high atomic number materials which might be nuclear materials, drugs, high explosive materials and other contrabands etc. High energy photon beams generally 6 and 9 MV can be used for scanning such materials. However, it is important to ensure that radiation level beyond the container scanner installation is within the permissible dose limit specified by the national competent authority for the protection of public and radiation workers. In this paper, challenges in the biological shielding during the installation of high energy X-ray system for scanning vehicles containing suspected materials are discussed. The purpose of the present study is to develop a methodology for shielding design and evaluation for container scanner installations. The basic concept pertaining to shielding evaluation of radiotherapy installations provided in National Council on Radiation Protection and Measurements (NCRP)/International Atomic Energy Agency (IAEA) reports are referred, and appropriately used to calculate optimized shielding thicknesses requirements for container scanner installation. Workload is estimated based on number of containers scanned, machine ON time and dose rate at 1m. The shielding evaluation includes use of beam stopper in the primary beam, scattering by heterogeneous metallic scrap materials or any other suspected materials contained in the vehicle and their impact on the thickness of shielding walls. A model lay out plan to be used for installation of container scanner is developed. A methodology for shielding evaluation for various protective walls and ceiling of this model is also discussed. The study provides basic requirement for designing a structural room for installing 9MV container scanner from radiological safety view point.

Computational thermodynamics-guided alloy design and phase stability in CoCrFeMnNi-based medium-and high-entropy alloys: An experimental-theoretical study

A computational thermodynamics approach has been employed to design CoCrFeMnNi-based medium- and high-entropy alloys (M/HEAs) with systematically varied compositions (Co((80-X)/2)Cr((80-X)/2)FeXMn10Ni10 with x = 30, 40, and 50 at.%) and phase stability. Since the formation of sigma phase, usually brittle and undesirable, is a common concern, when this class of alloys is subjected to elevated temperatures (600–1000 °C), predicting its formation becomes essential. Thus, its formation and the phase equilibria were studied using the CALPHAD method, and two empirical methods, namely, valence electron concentration (VEC) and paired sigma-forming element (PSFE). Isothermal aging treatments at 900–1100 °C for 20 h were performed, since CALPHAD and VEC/PSFE predictions diverged. Both prediction methods were compared with experimental characterization by a combination of scanning electron microscopy and high-energy synchrotron X-ray diffraction. The predictions from the VEC/PSFE and CALPHAD calculations (depending on the database used) were shown to be quite accurate.

The verification of the utility of a commercially available phantom combination for quality control in contrast-enhanced mammography.

Contrast-enhanced mammography is being increasingly implemented clinically, providing much improved contrast between tumour and background structures, particularly in dense breasts. Although CEM is similar to conventional mammography it differs via an additional exposure with high energy X-rays (≥ 40kVp) and subsequent image subtraction. Because of its special operational aspects, the CEM aspect of a CEM unit needs to be uniquely characterised and evaluated. This study aims to verify the utility of a commercially available phantom set (BR3D model 020 and CESM model 022 phantoms (CIRS, Norfolk, Virginia, USA)) in performing key CEM performance tests (linearity of system response with iodine concentration and background subtraction) on two models of CEM units in a clinical setting. The tests were successfully performed, yielding results similar to previously published studies. Further, similarities and differences in the two systems from different vendors were highlighted, knowledge of which may potentially facilitate optimisation of the systems.

Synchrotron X-ray diffraction studies of the internal load transfer in Ni–CrC metal matrix composites

Strengthening in metal matrix composites (MMCs) is primarily due to the load transfer from the compliant matrix to the stiff reinforcement. While internal load transfer has been studied for conventionally manufactured MMCs, the extent to which it may be affected by the preexisting defects in additively manufactured MMCs remain elusive. In this study, we performed uniaxial compression loading on cold sprayed Ni–CrC particulate-reinforced MMC. We observe significantly enhanced strength and ductility compared to the brittle behavior previously reported in tension for the same MMC. In contrast to the absence of load transfer in tension, the presence of initial defects did not preclude the internal load transfer in the composites under compressive loading. In-situ high-energy X-ray diffraction analysis revealed a relatively constant load partitioning in the elastic regime, which aligned well with predictions by the Eshelby's inclusion model. Furthermore, an internal load transfer was observed from the Ni matrix to the CrC reinforcement upon plastic deformation of the Ni matrix. Finite element modeling further confirmed this and demonstrated that localized tensile stress at the interface in the transverse direction resulted in the interfacial debonding and partial relaxation of the matrix. We also report reinforcing particle fracture upon further compression which in turn triggered the eventual failure of the MMC.

Unveiling the formation of nanotwin-mediated metastable ζ-hydrides in fatigued Zr-1Nb-0.01Cu cladding tube

The impact of internal pressure fatigue treatment on the α-Zr matrix and hydride precipitates in Zr-1Nb-0.01Cu cladding tube has been systematically investigated using synchrotron-based high-energy X-ray diffraction, electron backscatter diffraction and transmission electron microscopy techniques. The evolution in d-spacings of the basal plane (0002), the pyramidal plane {101¯1} and the prismatic plane {101¯0} at azimuths from 0° to 360° indicates that the internal pressure fatigue treatment has imparted a degree of plastic deformation upon the α-Zr phase, which is further confirmed by the presence of {101¯2} deformation twins within the α-Zr phase. Concurrently, the prior internal pressure fatigue treatment at 400 °C significantly increased nucleation sites for zirconium hydrides during the subsequent furnace cooling process. High-density dislocations can be seen in both the δ-hydride precipitate ({111}<110> type) and the α-Zr matrix ({101¯0}<a> type) near the hydride-matrix interface. Additionally, δ-hydride {111}<112¯> nanotwins were observed within the micro-sized δ-hydrides in the fatigued cladding tube, resulting from the nucleation and growth of intra-granular δ-hydrides at different regions of the same parent α-Zr grain. Furthermore, the HCP-structured ζ-hydride phase was detected at the δ-hydride nanotwin forefront along the growth direction and at the curved δ-hydride nanotwin boundaries, providing direct experimental evidence to the notion that the metastable ζ-hydride serves as the precursor to the stable δ-hydride phase during the precipitation process. The current experimental findings contribute to the fundamental understanding of microscopic mechanisms underlying the delayed hydride cracking and the stress-induced hydride reorientation in Zr alloys.

Effects of High Al Content on the Phase Constituents and Thermal Properties in NiCoCrAlY Alloys.

MCrAlY (M = Ni and/or Co) metallic coatings are essential for the protection of hot-end components against thermal and corrosion damage. Increasing the Al content is considered a feasible solution to improve the high-temperature performance of MCrAlY coatings. In this paper, the effects of high Al contents (12-20 wt.%) on the phase constituents and cast microstructures in MCrAlY alloys were studied by high-energy X-ray diffraction and electron microscopy techniques combined with phase equilibria calculations. High Al content improved the stability of β, σ, and α phases. Meanwhile, an evolution of the cast microstructure morphology from a dendrite structure to an equiaxed grain structure was observed. The thermal properties were analyzed, which were closely related to the phase constituents and solid-to-solid phase transitions at evaluated temperatures. This work is instructive for developing high-Al-content MCrAlY coatings for next-generation thermal barrier applications.

Energy Absorption and Beam Damage during Microfocus Synchrotron X-ray Diffraction.

In this study, we combine in situ fast differential scanning calorimetry (FDSC) with synchrotron X-ray measurements to study simultaneously the structure and thermophysical properties of materials. Using the example of the organic compound BCH-52, we show that the X-ray beam can heat the sample and induce a shift of the heat-flow signal. The aim of this paper is to investigate the influence of radiation on sample behavior. The calorimetric data is used to quantify the absorbed beam energy and, together with the diffraction data, reveal an irreversible damage of the sample. The results are especially important for materials with high absorption coefficients and for high-energy X-ray and electron beams. Our findings illustrate that FDSC combined with X-ray diffraction is a suitable characterization method when beam damage must be minimized.

In situ HEXRD experimental study and prediction of microstructures and internal stresses during heat treatment of carburized and carbonitrided low-alloyed steels

Thermochemical surface treatments of steels, such as carburizing and carbonitriding are used to improve mechanical properties, especially resistance to fatigue. Carbonitriding can achieve excellent properties, but the origins remain to be understood, as it has been less studied than carburizing. Fundamental understanding has to be established regarding the formation of microstructures and internal stresses as well as their couplings, during the cooling which follows the enrichment treatment.For this purpose, an original experimental method is introduced to follow in situ by High-Energy X-Ray Diffraction the phase transformation kinetics as well as the evolutions of the internal stresses during cooling, inside laboratory scale, 3 mm-thick samples with C and/or N composition gradients. The usual trends are confirmed regarding carburizing: the carbon-enriched case is the last to transform and the surface ends up with compression residual stresses. Conversely, for carbonitriding, unusual evolutions of microstructure and internal stresses are observed. The presence of nitrogen reduces the hardenability in the enriched case. This modifies the chronology of the phase transformations and this leads to tensile residual stresses at the surface.A coupled thermal, mechanical and metallurgical model predicting the phase transformation kinetics and the evolutions of internal stresses is set up. It achieves quantitative predictions and it shows that, in the studied cases, the phase transformation plasticity strains are the main origin of the residual stresses.

Dynamics of pore formation and evolution during multi-layer directed energy deposition additive manufacturing via in-situ synchrotron X-ray imaging: A case study on high-entropy Cantor alloy

Blown-powder directed energy deposition (DED) additive manufacturing is impeded for novel alloys processing by perceivable and detrimental porosity. During multi-layer depositions, however, mechanisms of pore formation and evolution remain elusive for developing pore mitigation strategies. Here, conduction-mode multi-layer DED process of an exemplary high-entropy Cantor alloy have been investigated in-situ by high-energy high-speed synchrotron X-ray imaging. Three new pore formation mechanisms are unveiled when depositing first layer and successive layers: gas pore induced by high-velocity powder injection into melt pool, pore generated from swirl shear of turbulent melt flow, and pore trapped by surface wave. Three pore formation mechanisms are reconfirmed: pore inheritance from feedstock powder, pore generation when laser remelting defect-sensitive locations of existing pore from previous layer or unmelted powder attached on the melt pool surface, and pore formation as cooling of melt pool. A unique mechanism for pore elimination is proposed: a counter-Marangoni melt flow is experimentally found in the stable melt pool and contributes to the prolonged pore lifetime at tens of milliseconds scale; pores are prone to coalesce into larger sizes in laser interaction zone and the adjacent location with circulation zone; coalesced larger pores driven by combined effect of Marangoni and buoyant forces easily get eliminated from melt pool. The results of pore formation and evolution dynamics revealed in Cantor alloy provide quantified experimental data for high-fidelity computational modeling and in-depth insights of porosity control for high-entropy alloy printing down to melt pool scale.

Microstructure and Phase Transformation Behavior of NiTiCu Shape Memory Alloys Produced Using Twin-Wire Arc Additive Manufacturing

NiTiCu thin walls were produced by twin-wire arc additive manufacturing (T-WAAM) using commercial NiTi and Cu wires as the feedstock materials. This approach aims to solve the problems typically associated with large phase transformation hysteresis in NiTi shape memory alloys. The microstructure, mechanical properties, and phase transformation behavior of the as-deposited NiTiCu alloy were comprehensively examined. The results revealed that the as-deposited NiTiCu alloy was well-formed, with its microstructure showed columnar, equiaxed, and needle-like grains, depending on the location within the deposited walls. The microhardness gradually increased from the first to the third layer. The Cu content was 20.80 at%, and Cu-based precipitates were formed in the as-deposited NiTiCu. The volume fractions and lattice parameters of the matrix and precipitates in the as-deposited NiTiCu material were analyzed using high-energy synchrotron X-ray diffraction. The martensitic phase was identified as a B19 crystal structure, and the as-deposited NiTiCu underwent a one-step B2-B19 phase transformation. The tensile strength and fracture strain were approximately 232 MPa and 3.72%, respectively. In particular, the addition of Cu narrowed the phase transformation hysteresis of the as-deposited NiTiCu alloy from 24.4 to 7.1 ℃ compared with conventional binary NiTi alloys. This study expands the potential of T-WAAM in modifying the phase transformation behavior of NiTi-based ternary alloys.

Development of a laser-driven shock compression platform for time-resolved XRD experiments at the ID09 beamline of the European Synchrotron Radiation Facility

ABSTRACT We present a newly developed laser-driven shock compression platform at the ID09 beamline of the European Synchrotron Radiation Facility (ESRF). This platform combines a custom high-power EKSPLA laser with ESRF's high-energy X-ray pulses to perform in situ, time-resolved X-ray diffraction (XRD) measurements in materials under well characterized, moderate pressure (up to 1 Mbar) and short-duration shock waves. Its purpose is to serve as a shock driver to study materials under dynamic pressure, focusing on phase transitions in condensed matter. We provide a detailed description of this platform's design and functionalities, along with preliminary experimental results obtained from iron and tin samples subjected to shock compression. These results not only demonstrate the platform's ability to acquire high-quality X-ray diffraction data but also highlight its potential for advancing research in material science and high-energy-density physics.

Strains and Stresses in Multilayered Materials Determined Using High-Energy X-ray Diffraction

This work explores the advantages and disadvantages of a methodology using high-energy X-ray diffraction to determine residual stresses in multilayer structures produced by atmospheric plasma spraying. These structures comprise a titanium alloy substrate (Ti64), a bonding layer (Ni-Al), and an abrasive coating (Al2O3). This study focuses on analyzing the residual stress gradients within these layers. The presented method is used to determine stresses across the entire thickness of multilayer structures. Experiments were carried out using a high-energy rectangular beam, operating in transmission mode, on the cross-section of the sample. The results indicate variable stresses throughout the depth of the sample, particularly near the layer interfaces. The semi-automatic methodology presented here enables us to follow stress evolution within the different layers, providing indications of the load transfer between them and at their interfaces. The sin2ψ method was used to analyze the diffraction data and to determine the stresses in each phase along the sample depth. However, interpreting results near the interfaces is complex due to the geometric and chemical effects. We present a discussion of the main advantages and disadvantages of the methodology for this kind of industrial sample.

The high energy X-ray probe (HEX-P): the future of hard X-ray dual AGN science

A fundamental goal of modern-day astrophysics is to understand the connection between supermassive black hole (SMBH) growth and galaxy evolution. Merging galaxies offer one of the most dramatic channels for galaxy evolution known, capable of driving inflows of gas into galactic nuclei, potentially fueling both star formation and central SMBH activity. Dual active galactic nuclei (dual AGNs) in late-stage mergers with nuclear pair separations &lt;10 kpc are thus ideal candidates to study SMBH growth along the merger sequence since they coincide with the most transformative period for galaxies. However, dual AGNs can be extremely difficult to confirm and study. Hard X-ray (&gt;10 keV) studies offer a relatively contamination-free tool for probing the dense obscuring environments predicted to surround the majority of dual AGN in late-stage mergers. To date, only a handful of the brightest and closest systems have been studied at these energies due to the demanding instrumental requirements involved. We demonstrate the unique capabilities of HEX-P to spatially resolve the soft and - for the first time - hard X-ray counterparts of closely-separated (∼2″−5″) dual AGNs in the local Universe. By incorporating physically-motivated obscuration models, we reproduce realistic broadband X-ray spectra expected for deeply embedded accreting SMBHs. Hard X-ray spatially resolved observations of dual AGNs—accessible only to HEX-P—will hence transform our understanding of dual AGN in the nearby Universe.

In-situ X-ray Fluorescence Analysis of In-plane Cerium-ion Distribution Under Humidity Gradients in Proton Exchange Membrane

Cerium ions are incorporated into proton exchange membranes (PEMs) of fuel cells to mitigate its chemical degradation caused by radical species. However, under fuel cell operating conditions, cerium ions move in in-plane direction in the cell by humidity gradient. This cerium ion transport results in cerium ion depletion leading to accelerated chemical degradation. This study developed an in-situ and operando measurement technique utilizing synchrotron high-energy X-ray fluorescence spectroscopy to monitor the cerium ion transport across the membrane under the in-plane humidity gradient. This method effectively tracks the dynamic behavior of cerium ions under fuel cell operating conditions.

Intermolecular Correlations in Liquid Lactic Acid Based on ab initio Molecular Dynamics Simulations Combined with High-Energy X-ray Diffraction Measurements

Intermolecular Correlations in Liquid Lactic Acid Based on ab initio Molecular Dynamics Simulations Combined with High-Energy X-ray Diffraction Measurements

The High-Energy X-ray Probe (HEX-P): the circum-nuclear environment of growing supermassive black holes

The High-Energy X-ray Probe (HEX-P): the circum-nuclear environment of growing supermassive black holes

Vertically Oriented Quasi-2D Perovskite Grown In-Situ by Carbonyl Array-Synergized Crystallization for Direct X-Ray Detectors.

Quasi-2D perovskite quantum wells are increasingly recognized as promising candidates for direct-conversion X-ray detection. However, the fabrication of oriented and uniformly thick quasi-2D perovskite films, crucial for effective high-energy X-ray detection, is hindered by the inherent challenges of preferential crystallization at the gas-liquid interface, resulting in poor film quality. In addressing this limitation, a carbonyl array-synergized crystallization (CSC) strategy is employed for the fabrication of thick films of a quasi-2D Ruddlesden-Popper (RP) phase perovskite, specifically PEA2MA4Pb5I16. The CSC strategy involves incorporating two forms of carbonyls in the perovskite precursor, generating large and dense intermediates. This design reduces the nucleation rate at the gas-liquid interface, enhances the binding energies of Pb2+ at (202) and (111) planes, and passivates ion vacancy defects. Consequently, the construction of high-quality thick films of PEA2MA4Pb5I16 RP perovskite quantum wells is achieved and characterized by vertical orientation and a pure well-width distribution. The corresponding PEA2MA4Pb5I16 RP perovskite X-ray detectors exhibit multi-dimensional advantages in performance compared to previous approaches and commercially available a-Se detectors. This CSC strategy promotes 2D perovskites as a candidate for next-generation large-area flat-panel X-ray detection systems.

Structure and particle surface analysis of Li2S–P2S5–LiI-type solid electrolytes synthesized by liquid-phase shaking

AbstractLi2S–P2S5–LiI-type solid electrolytes, such as Li4PS4I, Li7P2S8I, and Li10P3S12I, are promising candidates for anode layers in all-solid-state batteries because of their high ionic conductivity and stability toward Li anodes. However, few studies have been conducted on their detailed local structure and particle surface state. In this study, Li7P2S8I (Li2S: P2S5:LiI = 3:1:1) solid electrolytes as the chemical composition were synthesized by mechanical milling and liquid-phase shaking, and their local structures were analyzed by transmission electron microscopy. The particle surface states were analyzed by X-ray photoelectron spectroscopy, high-energy X-ray scattering measurements, and neutron total scattering experiments. The results showed that Li7P2S8I solid electrolytes are composed of nanocrystals, such as Li4PS4I, LiI, Li10P3S12I and an amorphous area as the main region, indicating that the crystalline components alone do not form ionic conductive pathways, with both the amorphous and crystalline regions contributing to the high ionic conductivity. Moreover, the ionic conductivity of the crystalline/amorphous interface of the glass-ceramic was higher than that of the Li2S–P2S5–LiI glass. Finally, an organic-solvent-derived stable surface layer, which was detected in the liquid-phase shaking sample, served as one of the factors that contributed to its high stability (which surpassed that of the mechanically milled sample) toward lithium anodes. We expect these findings to enable the effective harnessing of particle surface states to develop enhanced sulfide solid electrolytes.

The effect of double intercritical annealing on micromechanical behavior of a medium Mn transformation induced plasticity steel investigated by in situ high energy X-ray diffraction

The micromechanical behavior of a medium Mn transformation induced plasticity (TRIP) steel processed by intercritical annealing (IA) and double intercritical annealing (DIA) has been investigated by using in situ high energy X-ray diffraction during uniaxial tensile deformation. The results show that the ultimate tensile strength (UTS) and total elongation are 777.1 MPa and 39.6 % for IA and 953.6 MPa and 59.1 % for DIA, and that the product of UTS and total elongation is 30.8 GPa·% for IA and 56.4 GPa·% for DIA, respectively. Discontinuous phase transformation from austenite to martensite leads to Portevin-Le Châtelier (PLC) band propagation for both IA and DIA. The pronounced TRIP effect takes place in DIA step by step during deformation and contributes to higher strain hardening, which results in almost doubling the product of UTS and total elongation. The stepwise phase transformation highly corresponds to the lattice strain evolution of ferrite and austenite, indicating that load partitioning occurs during the deformation. The change of grain structure generated by different heat-treatments correlate with the load partitioning, thereby inducing large discrepancy in micromechanical behavior. The present investigation provides a deeper fundamental understanding of the effect of double inter-critical annealing on micromechanical behavior and effective engineering strategies for improving the product of UTS and total elongation for the medium Mn TRIP steels.