High-energy Synchrotron X-ray Research Articles

Non-Destructive Analysis of a High-Power Capacitor Using High-Energy X-ray Compton Scattering

Changes in the internal state of a high-power capacitor during progressive charge–discharge cycling were measured non-destructively using high-energy synchrotron X-ray Compton scattering. The stacked structure of a laminated capacitor was clearly indicated by a Compton scattered X-ray intensity analysis and a line shape (S-parameter) analysis of a Compton scattered X-ray energy spectrum. Moreover, apparent differences in the progress of charge and discharge cycles were observed in the correlation between Compton scattered X-ray intensities and S-parameters obtained from the center and edge positions within the in-plane of the electrode. This difference in the correlation was obtained from the shifting of the stacked structure at the edge position, induced by the drift of the electrolyte material within the capacitor cells.

Strain-dependent phase transformation mapping of diffusion-bonded nanocrystalline aluminum-magnesium by high-energy synchrotron X-rays

This study highlights the capability of high-energy synchrotron X-rays to investigate polymorphous phase transformation upon nanostructuring and diffusion bonding of Al and Mg through high-pressure torsion. The measurements providing diffraction peak profiles at a series of local positions over the sample volume allow mapping of gradual yet significant structural changes in the Al-Mg nanocrystalline alloy. The diffraction peaks involve apparent grain refinement broadening and compositional broadening with increasing shear strain. The results reveal strain-dependent transformations between f.c.c and h.c.p. phases with a sharp dissolution at strains of ∼2500 and subsequent homogenization towards the formation of an Al supersaturated solid solution with the Mg concentration of ∼14–15 at.%.

Improving the ductility in laser welded joints of CoCrFeMnNi high entropy alloy to 316 stainless steel

Dissimilar joining involving high entropy alloys is currently being explored to evaluate the suitability of these novel advanced engineering materials in structural applications. Recently, joining of a CoCrFeMnNi high entropy alloy to 316 stainless steel was successfully attempted. However, the joint ductility was limited by the lack of deformation experienced by the cold-rolled CoCrFeMnNi base material during tensile loading. In this work, it is shown that by simply changing the base material condition, from cold-rolled to annealed, it is possible to significantly improve the joint fracture strain from ≈ 5 to ≈ 10 %, while preserving the strength at ≈ 450 MPa. Using electron microscopy, high energy synchrotron X-ray diffraction and mechanical testing aided by digital image correlation, the microstructure evolution across the welded joint is assessed and correlated to its mechanical performance. Moreover, thermodynamic calculations considering the compositional changes across the fusion zone were used to predict the microstructure evolution of this region.

Unveiling Non-isothermal Crystallization of CaO-Al2O3-B2O3-Na2O-Li2O-SiO2 Glass via In Situ X-ray Scattering and Raman Spectroscopy.

The crystallization in glasses is a paradoxical phenomenon and scarcely investigated. This work explores the non-isothermal crystallization of a multicomponent alumino-borosilicate glass via in situ high-energy synchrotron X-ray diffraction, atomic pair distribution function, and Raman spectroscopy. Results depict the crystallization sequence as Ca3Al2O6 and CaSiO4 followed by LiAlO2 with the final compound formation of Ca3B2O6. These precipitations occur in a narrow temperature range and overlap, resulting in a single exothermic peak in the differential scanning calorimetry thermogram. The concurrent nucleation of Ca3Al2O6 and CaSiO4 is intermediated by their corresponding hydrates, which have dominantly short-range order. Moreover, the crystallization of LiAlO2 and Ca3B2O6 is strongly linked with the changes of structural units during the incubation stage in non-isothermal heating. These findings clarify the crystallization of multicomponent glass, which have been inferred from ex situ reports but never evidenced via in situ studies.

Tailoring the chemical heterogeneity of Mn-modified 0.75BiFeO3-0.25BaTiO3 ceramics for piezoelectric sensor applications

The Mn-modified 0.75BiFeO3-0.25BaTiO3 (75BFBTMn) piezoelectric ceramic possesses a high depolarization temperature of 500 °C and a large piezoelectric coefficient of 110 pC/N, showing the potential for high temperature piezoelectric sensors. However, 75BFBTMn ceramic usually suffers dielectric degradation and abrupt drop of piezoelectric coefficient in the range of 300 °C to 500 °C. Combined the high-energy synchrotron X-ray diffraction analysis with Backscatter-SEM results, it is demonstrated that the electrical thermal instability is owing to the existence of chemical inhomogeneity. The Air-annealing treatment is able to decrease the volume fraction of pseudo-cubic phase and the lattice distortion, removes the chemical inhomogeneity in the grain and free Bi2O3 at grain boundary, and then eliminates dielectric anomalies and piezoelectric degradation with temperature. These results indicate that air-annealing is a simple but effective method to eliminate the chemical inhomogeneity in 75BFBTMn ceramics, thereby improving the property thermal stability for high temperature piezoelectric sensor applications.

Fatigue crack propagation behavior of a micro-bainitic TRIP steel

Controlling the grain size of steels is an effective way for tailoring their mechanical properties, such as yield strength, impact toughness, and ductility. In this study, a new industrial thermomechanical treatment was applied to a low-alloyed TRIP-assisted bainitic steel 13MnSiCr7 to achieve a substantial microstructural refinement. In this way the average grain size of the new micro-bainitic steel was decreased from ∼25 μm to ∼5 μm. Fatigue tests were carried out in order to investigate the influence of this new thermomechanical treatment on crack propagation behavior. Besides electron backscatter diffraction (EBSD), vibrating sample magnetometry (VSM), and high-energy synchrotron X-ray diffraction (HEXRD) were used to study the microstructure in the vicinity of the fatigue crack tip. The applicability of each method for detecting the martensitic transformation is discussed. In addition, the contribution of the martensitic transformation to fracture toughness was assessed on the basis of the results obtained by HEXRD.

In Situ Analytical Methods for the Characterization of Mechanochemical Reactions

The interest in mechanochemical reactions and their fields of application have increased enormously in recent times. Mechanically activated reactions offer the advantage of cost-efficiency as well as environmentally friendly syntheses routes. In contrast to thermally induced processes, the energy transfer via the milling media takes place on a local scale. This leads to unique reaction pathways, which often also result in the formation of metastable phases. For the understanding of reaction pathways on a mechanistic level, it is very important to follow the processes taking place in the grinding jar during milling. Besides the measurement of pressure and temperature changes during a mechanochemical reaction, in situ high energy synchrotron X-ray powder diffraction and Raman spectroscopy experiments have been successfully implemented over the last 10 years. This review will highlight the developments which were achieved in the field of in situ monitoring of mechanochemical reactions and their input to the understanding of mechanochemistry.

Ultrafast Nanocrystallization of BaF2 in Oxyfluoride Glasses with Crystal-like Nanostructures: Implications for Upconversion Fiber Devices

Transparent glass–ceramic fibers containing fluoride nanocrystals are attracting attention as upconversion devices. In this paper, a material design is proposed that eliminates the need for heat treatment processes. The impact of short- to medium-range structures on the crystallization of glasses was investigated to enable nanocrystallization in the quenching process via ultrafast nucleation. In this study, the short- to medium-range structures of (33.3 – x/3)BaF2–xZnO–(66.7 – 2x/3)B2O3 glasses were investigated by 11B- and 19F-magic-angle spinning nuclear magnetic resonance spectroscopy, molecular dynamics simulations, and the high-energy synchrotron X-ray diffraction. After heat treatment, glasses with x > 40 formed BaF2 nanocrystals with a diameter of ∼5 nm and a small particle size distribution (<1 nm). Based on the high-energy synchrotron X-ray diffraction, the critical size of the nuclei was estimated to be 4 nm, which was similar to the size of the precipitated crystals. Obvious selectivity in the binding was observed: F– preferred Ba2+ and O2– preferred B3+, whereas Zn2+ was bound to both anions. The binding selectivity caused a bicontinuous structure of oxide and fluoride domains, and the fluoride-related structure factors and bond distance were very similar to the peak positions of the precipitated crystals. Er3+-doped glasses with x > 40 showed upconversion luminescence with a spectrum similar to that of BaF2. These results suggested the pre-existence of a crystal-like structure with a composition, density, and ordering similar to those of the precipitated crystals. Moreover, glass with the modified composition was successfully crystallized during press-quenching of the melt and the fiber drawing process. These results could facilitate the production of photonic components such as nanocrystallized glass fibers and microspheres for upconversion lasers as well as a wide variety of glass–ceramic products.

Lattice Strain and Surface Activity of Ternary Nanoalloys under the Propane Oxidation Condition.

The ability to harness the catalytic oxidation of hydrocarbons is critical for both clean energy production and air pollutant elimination, which requires a detailed understanding of the dynamic role of the nanophase structure and surface reactivity under the reaction conditions. We report here findings of an in situ/operando study of such details of a ternary nanoalloy under the propane oxidation condition using high-energy synchrotron X-ray diffraction coupled to atomic pair distribution function (HE-XRD/PDF) analysis and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The catalysts are derived by alloying Pt with different combinations of second (Pd) and third (Ni) transition metals, showing a strong dependence of the catalytic activity on the Ni content. The evolution of the phase structure of the nanoalloy is characterized by HE-XRD/PDF probing of the lattice strain, whereas the surface activity is monitored by DRIFTS detection of the surface intermediate formation during the oxidation of propane by oxygen. The results reveal the dominance of the surface intermediate species featuring a lower degree of oxygenation upon the first C-C bond cleavage on the lower-Ni-content nanoalloy and a higher degree of oxygenation upon the second C-C bond cleavage on the higher-Ni-content nanoalloy. The face-centered-cubic-type phase structures of the nanoalloys under the oxidation condition are shown to exhibit Ni-content-dependent changes of lattice strains, featuring the strongest strain with little variation for the higher-Ni-content nanoalloy, in contrast to the weaker strains with oscillatory variation for the lower-Ni-content nanoalloys. This process is also accompanied by oxygenation of the metal components in the nanoalloy, showing a higher degree of oxygenation for the higher-Ni-content nanoalloy. These subtle differences in phase structure and surface activity changes correlate with the Ni-composition-dependent catalytic activity of the nanoalloys, which sheds a fresh light on the correlation between the dynamic change of atomic strains and the surface reactivity and has significant implications for the design of oxidation catalysts with enhanced activities.

Extreme conditions research using the large-volume press at the P61B endstation, PETRA III.

Penetrating, high-energy synchrotron X-rays are in strong demand, particularly for high-pressure research in physics, chemistry and geosciences, and for materials engineering research under less extreme conditions. A new high-energy wiggler beamline P61 has been constructed to meet this need at PETRA III in Hamburg, Germany. The first part of the paper offers an overview of the beamline front-end components and beam characteristics. The second part describes the performance of the instrumentation and the latest developments at the P61B endstation. Particular attention is given to the unprecedented high-energy photon flux delivered by the ten wigglers of the PETRA III storage ring and the challenges faced in harnessing this amount of flux and heat load in the beam. Furthermore, the distinctiveness of the world's first six-ram Hall-type large-volume press, Aster-15, at a synchrotron facility is described for research with synchrotron X-rays. Additionally, detection schemes, experimental strategies and preliminary data acquired using energy-dispersive X-ray diffraction and radiography techniques are presented.

Revealing the interdependence of microstructure evolution, micromechanics and macroscopic mechanical behavior of multi-phase medium Mn steels

The mechanical response, on a microscopic and macroscopic level, and the deformation-induced martensitic transformation (DIMT) were investigated in multi-phase medium Mn steels (MMnS) with 6, 8 and 9 wt% Mn using in situ high-energy synchrotron x-ray diffraction during tensile loading. Prior to the in-situ analysis, a similar heat treatment finishing with an intercritical annealing was imposed on all MMnS. The initial microstructure prior to tensile loading was investigated by electron backscatter diffraction analysis. The volume fraction of austenite (γ) after the heat treatment decreases from 60.2% to 50.7%, and 23.6% with increasing Mn content from 6 to 8 and 9 wt% Mn, respectively. This is mainly due to the difference in the formation of athermal α′-martensite. Athermal ε-martensite also formed in the MMnS with 8 and 9 wt% Mn, whereas no athermal ε-martensite formed in the MMnS with 6 wt% Mn. The alloys have quite different deformation behavior due to the different microstructures, and the majority of the load is carried by the phase that forms a continuous network throughout the steel, which in turn influences the DIMT. These results reveal the importance of assessing both phase-specific strain/stress and the inherent mechanical stability of the austenite in order to predict the macroscopic mechanical properties of the steel. As an example, this is witnessed by the comparison of MMnS9 and MMnS8. Austenite in MMnS9 bears about half the load as compared to austenite in MMnS8 during early deformation due to a continuous network of athermal α′-martensite resulting in significant load partitioning from austenite to α′-martensite. Thus, the mechanical driving force for DIMT in MMnS9 is reduced and therefore causes lower DIMT kinetics in MMnS9 than in MMnS8, even though MMnS9 has lower inherent austenite stability.

Method for in situ texture investigation of recrystallization of Cu and Ti by high-energy synchrotron X-ray diffraction

Abstract High-energy synchrotron radiation has been used to study in situ annealing of cold-rolled Cu and Ti. The measurements were performed using a high-vacuum furnace in transmission geometry and an area detector. The diffraction images were subsequently processed to extract the orientation distribution. The recrystallization process could be followed with a time resolution of the order of 10 s, and good pole figures could be obtained from the very limited amount of data in single diffraction images. The pole figures compare favorably with pole figures of the same material measured ex situ with a conventional pole figure goniometer. For Cu, a rapid and complete change from a typical rolling texture to a cube texture was observed after annealing for 20 min at 650 °C. For Ti, changes were more subtle with a tendency for c-axes to diminish near the normal direction, as well as for a-axes to become aligned with the rolling direction. The method makes it feasible to study the kinetics of recrystallization with quantitative texture analysis.

Hydrogen solubility in FeSi alloy phases at high pressures and temperatures

AbstractLight elements alloying with metallic Fe can change the properties and therefore play a key role in the structure and dynamics of planetary cores. Hydrogen and silicon are possible light elements in the rocky planets’ cores. However, hydrogen storage in Fe-Si alloy systems remains unclear at high pressures and high temperatures because of experimental difficulties. Taking advantage of pulsed laser heating combined with high-energy synchrotron X-ray diffraction, we studied reactions between FeSi and H in laser-heated diamond-anvil cells (LHDACs) up to 61.9 GPa and 3500 K. We found that under H-saturated conditions the amount of H alloying with FeSi (0.3 and &amp;lt;0.1 wt% for the B20 and B2 structures, respectively) is much smaller than that in pure Fe metal (&amp;gt;1.8 wt%). Our experiments also suggest that H remains in the crystal structure of FeSi alloy when recovered to 1 bar. Further density functional theory (DFT) calculations indicate that the low-H solubility likely results from the highly distorted interstitial sites in the B20 and B2 structures, which are not favorable for H incorporation. The recovery of H in the B20 FeSi crystal structure at ambient conditions could open up possibilities to understand geochemical behaviors of H during core formation in future experiments. The low-H content in FeSi alloys suggests that if a planetary core is Si-rich, Si can limit the ingassing of H into the Fe-rich core.

Unveiling microstructure-property correlations in nuclear materials with high-energy synchrotron X-ray techniques

Understanding the microstructure-property correlation is critical for the performance evaluation of in-service materials and the development of advanced materials for nuclear reactor applications. Experimental studies are challenging for nuclear materials which are often hazardous. Recent developments in high-energy synchrotron X-ray (HEX) techniques offer the potential to address this challenge, by providing direct observations of internal responses to external stimuli in bulk-like materials, through in situ or 3D measurements. In this review, developments in HEX techniques are introduced and recent applications in nuclear materials are presented. The results offer unprecedented insights into materials performance and provide unique input to computational models.

On the devitrification of Cu–Zr–Al alloys: Solving the apparent contradiction between polymorphic liquid-liquid transition and phase separation

In this work, the crystallization pathways and kinetics of the Cu47.5Zr45.1Al7.4 bulk metallic glass (BMG) are studied systematically using a broad collection of laboratory and synchrotron-based techniques, such as differential scanning calorimetry, transmission electron microscopy, in situ high-energy synchrotron X-ray diffraction (HEXRD), simultaneous small- and wide-angle X-ray scattering, and atom probe tomography. The crystallization sequence during heating at conventional slow rates and isothermal annealing near the glass transition temperature was determined to consist in preferential formation of (Cu, Al)10Zr7 followed by the formation of CuZr2 and AlCu2Zr induced by long-range atomic diffusion. In situ HEXRD shows that the formation of the latter two phases is accompanied by the partial dissolution of the primary Cu-rich phase. Microstructural characterizations of annealed samples suggest that a new liquid phase with enhanced local order and obscure compositional changes has formed from the homogeneous supercooled liquid before crystallization. A concept analogous to the disorder-to-order transition in crystalline materials is applied here to describe the observed transition in liquid, resolving the longstanding apparent contradiction between observing a nanoscale phase separation versus a liquid–liquid phase transition during devitrification. Furthermore, we suggest that the formation of an intermediate liquid phase prior to crystallization is the structural origin of the rapid devitrification kinetics during the primary crystallization. On the basis of our combined experimental results, a scheme is proposed to generalize the complex multistep devitrification mechanisms of the Cu47.5Zr45.1Al7.4 BMG during isothermal annealing or slow heating. This work may provide new insights into the crystallization behavior and thermal stability of Cu–Zr–Al BMGs in terms of thermodynamics and kinetics and might lead to deeper understanding of the underlying mechanisms of the often observed rapid crystallization processes of deeply undercooled metallic liquids.

In-situ high-energy X-ray diffraction and crystal plasticity modeling to predict the evolution of texture, twinning, lattice strains and strength during loading and reloading of beryllium

Deformation behavior of beryllium during compressive loading and cross-reloading is studied using in-situ high energy synchrotron X-ray diffraction microscopy and crystal plasticity modeling. The evolution of texture, twinning, elastic lattice strains, and flow stress are measured and compared with the predictions of an advanced elastic-plastic self-consistent (EPSC) crystal plasticity model. The model is initialized with the experimentally measured texture and residual stress produced by a simulation of cooling and calibrated to establish a set of model parameters using a portion of the measured data. The rest of the measured data is used for validation of the model. It is shown that the model is sufficiently flexible to reproduce the particularities pertaining to the complex strain-path-change and strain rate sensitive deformation of the material including the evolution of texture, twinning, lattice strains, transients in the stress-strain response, and anisotropic hardening with great accuracy using a single set of model parameters. From the comparison of the experimental data and predictions, we infer that the shifts in active deformation mechanisms between the slip systems from soft to hard and vice versa as well as between twinning to de-twinning are primarily responsible for drastic changes in the flow stress from one path to another. In particular, deformation twins form during compressive in-plane loading followed either by de-twinning during compressive cross-reloading in the through-thickness direction or by forming additional twin variants with some de-twinning of the existing variants during a compressive cross-reloading in another in-plane direction. The shifts in active deformation mechanisms are a consequence of changes in texture relative to the compression direction mediated with the deformation history and strain rate dependent dislocation density evolution governing hardening. The secondary effects improving the predictions come from accounting for residual stress, slip system-level backstress, and latent hardening.

Hydrogen-Induced Micro-Strain Evolution in Super Duplex Stainless Steel—Correlative High-Energy X-Ray Diffraction, Electron Backscattered Diffraction, and Digital Image Correlation

The local lattice strain evolution during electrochemical hydrogen charging and mechanical loading in 25Cr-7Ni super duplex stainless steel were measured in-situ using synchrotron high-energy x-ray diffraction. Post-mortem electron backscattered diffraction analysis showed that the austenite phase underwent plastic deformation in the near-surface due to hydrogen-enhanced localized plasticity, where the ferrite phase experienced hardening. In bulk regions, the ferrite was the softer phase, and the austenite remained stiff. Digital image correlation of micrographs recorded, in-situ, during mechanical tensile testing revealed intensified plastic strain localization in the austenite phase, which eventually led to crack initiation. The absorption of hydrogen caused strain localization to occur primarily in austenite grains.

Oxide-stabilized microstructure of severe plastically deformed CuCo alloys

Nanocrystalline materials are well known for their beneficial mechanical and physical properties. However, it is of utmost importance to stabilize the microstructure at elevated temperatures to broaden the window of application e.g. by pinning grain boundaries through impurities or oxides. CuCo alloys, severe plastically deformed using high-pressure torsion, were used to investigate the evolution of oxides upon annealing. These investigations were performed using electron microscopy, synchrotron high-energy X-ray scattering and atom probe tomography. Monitoring the evolution of oxides by in-situ small angle scattering investigations indicates the growth of primary oxides as well as the formation of another species of oxide at elevated temperatures. Slightly different coarsening can be observed in heat-treated samples, which can be traced back to the influence of different oxide amounts. The initially supersaturated CuCo matrix changes by the decomposition process as well as Co- and Cu-based oxides formation and growth. It has been found that the major number of oxides which are present after annealing, can already be found in the starting materials.

Study of the Correlation between Premartensitic Transformation and Invar Effect in Femn Alloys by Synchrotron High-Energy X-Ray Diffraction

Study of the Correlation between Premartensitic Transformation and Invar Effect in Femn Alloys by Synchrotron High-Energy X-Ray Diffraction

Study of the Correlation between Premartensitic Transformation and Invar Effect in Femn Alloys by Synchrotron High-Energy X-Ray Diffraction

Study of the Correlation between Premartensitic Transformation and Invar Effect in Femn Alloys by Synchrotron High-Energy X-Ray Diffraction