High-energy Synchrotron Radiation Research Articles

S152 Residual Stress Analysis of Aluminium Welds with High Energy Synchrotron Radiation at the HARWI II Beamline

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S109 Simultaneous Measurement of Imaging and Strain of Fatigue Crack in Steel Bars Using High-Energy Synchrotron Radiation

S109 Simultaneous Measurement of Imaging and Strain of Fatigue Crack in Steel Bars Using High-Energy Synchrotron Radiation

Using X-Ray Microtomography for Characterisation of Catalyst Particle Pore Structure

The use of a high-energy synchrotron radiation source has permitted the introduction of high-resolution X-ray microtomography imaging as a method of non-intrusive and non-destructive three-dimensional (3D)visualized characterization of porous media. The use of a combination of X-ray microtomography, along with mercury porosimetry and Low Melting Point Alloy (LMPA) intrusion potentially provides a more complete approach to more accurate catalyst pore structure characterisation and modelling. This combined approach has been applied to the study of an industrial alumina catalysts support. The data collected from the study has been used to develop and generate an improved pore network model basis, in which both heterogeneity and hierarchy are considered in obtaining an improved pore architecture and pore size distribution.

Atomic structure of Zr–Cu–Al and Zr–Ni–Al amorphous alloys

Abstract We report on the atomic structure via pair distribution function (PDF) analysis of metallic glasses of the Zr–Cu–Al and Zr–Ni–Al families. The PDFs were evaluated from the X-ray diffraction data. Transmission X-ray diffraction spectra of the investigated samples were measured using monochromatic, high-energy synchrotron radiation. In this work we demonstrate the effect of composition on the pair distribution functions. A variation of first PDF peak shape was observed on modification of Cu and Al content. A split of the first PDF peak was found to be more pronounced in Zr–Ni–Al than in Zr–Cu–Al glasses suggesting differences in their atomic structures.

In-situ small-angle X-ray scattering study of the precipitation behavior in a Fe-25 at.%Co-9 at.%Mo alloy

Fe–Co–Mo alloys show extraordinary mechanical properties which make them potential candidates for various high-performance applications. In the present study, for the first time, the precipitation behavior in a Fe-25 at.%Co-9 at.%Mo alloy was studied by small-angle X-ray scattering using high-energy synchrotron radiation. The specimens were isothermally aged in an in-situ furnace. The small-angle X-ray scattering patterns showed scaling behavior and were evaluated by employing a model function from the literature. This approach provides information about the characteristic length scale and the volume fraction of the precipitates in the alloy.

Effect of wettability on bubble formation at gas nozzle under stagnant condition

Injection of gas microbubbles into mercury might be effective to mitigate pressure waves generating and propagating in liquid mercury target for MW-class spallation neutron sources. The effect of mitigation is very dependent on the bubble conditions; size, population, etc. It is important to make clear bubble formation behavior from a nozzle for development of making suitable gas microbubbles into mercury. Visualization of microbubbles in mercury was carried out by refraction-enhanced imaging with high-energy synchrotron radiation X-rays at SPring-8 to observe the bubble formation behavior at micro-gas nozzle of 100 μm in inner diameter and 200 μm in outer diameter. The bubble formation behavior in mercury was quite different from that in water. A constant taking account of the wettability and interfacial tension force between liquid and solid metals in an equation of force balance around bubble was identified by visualized bubble size. The bubble size under mercury flowing condition was estimated from the force balance equitation.

Analysis of trace elements in gold alloys by SR-XRF at high energy at the BAMline

Measuring in a non-destructive way the characteristic trace elements of the metal allows following the circulation of gold in the past. The aim of this work is to probe the possibilities of X-ray fluorescence with high energy synchrotron radiation (SR-XRF) at the BAMline at BESSY II to determine the concentration of Pt in ancient gold alloys. A HP-Ge detector was used to measure the Pt K-lines excited with an incident energy of 79.5keV. Data processing was done by subtraction of a Pt free gold standard spectrum from the spectrum of the sample. Depending on the sample composition, the MDL ranges between 40 and 90ppm. The first results obtained for a small set of gold alloys of different thickness, size and composition showed that high energy SR-XRF is a significant method for the non-destructive determination of Pt in gold.

Measurement of Strain Distribution around Weld Zone for Railway Carbody Structure Using High-Energy Synchrotron Radiation

The railway carbody structure for commuter and suburban train services in Japan is often made of austenitic stainless steel, which is used in the form of thin metal sheets manufactured by cold rolling. Spot welding and laser welding at lapped joints are used in the construction of such carbodies, but it is difficult to observe the strain distribution around these weld zones, which represent the critical area of the body structure’s strength. The objective of this study is to ascertain the strain distribution in the stainless steel around the weld zone of the carbody structure. To enable observation of this distribution, a strain scanning method using high-energy synchrotron radiation was applied to the strain measurement of austenitic stainless steel. The transmission method was applied in order to observe the internal weld zone. Using this method, we can measure the strain distribution from the surface to the inside of the weld zone. A lapped joint specimen, prepared by welding 2-mm-thick plates using the laser welding method, was used for measurement. Austenitic stainless steel generally poses problems in the measurement of strain due to its coarse grain and crystal texture. The gage volume in this measurement had a width of 3 mm and a height of 0.15 mm. The measurement provides the strain distribution of both residual strain and strain under loading, and the results obtained successfully show the distribution of strain in the weld zone. In addition, the differing tendency between the distribution of residual strain and that of strain under loading is clarified. The full width at half maximum (FWHM) value shows a difference between the tendency of the measured value of the weld zone and that of the base material.

First Results of the DITO-Experiment at the HARWI II Beamline at GKSS/DESY

At the HARWI II beamline at the GKSS outstation at DESY a new experiment for position sensitive diffractometry and tomography called DITO was built and commissioned this year. Due to the available high energy synchrotron radiation with photon energies up to 100 keV it is possible to investigate the bulk of metallic samples of a few mm thickness with both methods. The diffractometry detector allows the investigation of the phase composition as well as phase sensitive determination of residual stresses with a spatial resolution of 6 μm while the tomography detector can either measure a whole tomogram in high resolution mode with a spatial resolution of 2 μm within 3 to 4 hours or in high speed mode recording a whole tomogram within 15 seconds with a spatial resolution of 40 μm.

<i>In Situ</i> Investigation of the Deformation Behaviour of the Wrought Mg Base Alloy AZ31 Using Energy Dispersive Synchrotron Diffraction

The deformation behavior of the magnesium base alloy AZ31 was studied by means of energy dispersive diffraction using high energy synchrotron radiation. The investigations were performed at the EDDI-beamline operated by the Hahn-Meitner-Institute at Bessy II, Berlin. In-situ stress analyses were carried out for samples subjected to purely elastic as well as elasto-plastic 4- point-bending. In addition reversely loaded states were investigated. The results impressively illustrate the potential of the energy dispersive diffraction analysis processed in transmission mode for residual stress analysis of challenging material states. Inhomogeneous loading and residual stress distributions with respect to the bending height of the prestressed bars were determined for the highly textured material state indicating different predominant deformation mechanisms during tensile loading and compressive loading, respectively. After load inversion also the predominant deformation mechanisms reverse.

<i>In Situ </i>Synchrotron Measurement of Internal Stresses in Solid-Oxide Fuel Cell during Red-Ox Cycle

The internal stress in solid-oxide fuel cells (SOFCs) was evaluated during the thermal, reduction and re-oxidation cycles by using high-energy X-ray synchrotron radiation of about 70 keV at Beam line BL02B1 of SPring-8. The oxidized cell has a compression of about 400 MPa in the c-ScSZ electrolyte and a tension of 50-100 MPa in the NiO-YSZ anode at room temperature. In-situ measurement during the thermal cycle in an air atmosphere, the internal stress decreased with increasing temperature, becoming approximately zero at 1000 K. After the thermal cycle, the internal stress returned to its initial value. In the measurement during the reduction cycle, the internal stress was smaller than that measured during the cooling cycle after the anode was reduced from NiO-YSZ to Ni-YSZ. In the re-oxidation cycle of a reduced cell, the internal stress in the electrolyte went into tension above 800 K when the anode was re-oxidized from Ni-YSZ to NiO-YSZ. This tensile stress is responsible for possible fracture of unit cells in SOFCs.

Relationship between optical dielectric constant and XPS relative chemical shift of 1s and 2p levels for dielectric compounds

We find a new relationship between the optical dielectric constant of Al dielectric films and their chemical shifts measured by X-ray photoelectron spectroscopy (XPS). We measure the difference between core-level binding energy shift for Al 1s and core-level binding energy shift for Al 2p, ΔE1s - ΔE2p, for AlN using high-resolution high-energy synchrotron radiation. We find that ΔE1s - ΔE2p correlates well with the optical dielectric constants of Al, AlN, and Al2O3. This is consistent with the case of our previously reported Si compounds. First-principles calculations are performed to determine the mechanism behind the observed correlation.

Non-destructive depth profile analysis for surface and buried interface of Ge thin film on Si substrate by high-energy synchrotron radiation x-ray photoelectron spectroscopy

Non-destructive depth profile analysis with better depth resolution is required for the characterization of nano-materials and their fabrication. X-ray photoelectron spectroscopy (XPS) is the typically non-destructive analysis, however, XPS with fixed excitation energy source cannot provide depth profile without additional technique, such as ion beam sputtering. On the other hand, analyzing depth of XPS can be varied with the energy tunable excitation source, such as the synchrotron-radiation (SR), since the escape depth of the photoelectrons depends on their kinetic energy. We can obtain the XPS spectra from different analyzing depth by varying excitation energy. This technique can provide depth profile non-destructively. In the present study, Ge thin films on Si substrate has been analyzed to obtain depth profile of the thin film and buried interface of Ge/Si under the film.

Crystallization behavior in a highly driven marginal glass forming alloy

Al 90Sm 10, a marginal glass former, was rapidly solidified using Cu-block single roller melt spinning at wheel speeds of 30 and 40 m/s. The product phases of rapid solidification were identified and analyzed using high energy synchrotron X-ray diffraction (HEXRD), high resolution transmission electron microscopy, and atom probe tomography. The as-quenched structure consists of a saturated amorphous phase and nanocrystalline Al with typical length scale of about 5 nm. The appearance of a pre-peak on HEXRD diffraction patterns and a low activation energy for first crystallization as determined using the Kissinger and Ozawa methods indicate some local ordering in the amorphous phase. The devitrification phase transformation path was determined using in situ high energy synchrotron radiation. Three phases, MS1, H1, and Al 4Sm, were identified during decomposition of the amorphous phase. MS1, H1 and Al 4Sm are cubic, hexagonal and orthorhombic metastable phases, respectively.

Strain Measurement under Loading in Laser Weld on Austenitic Stainless Steel Using High-Energy Synchrotron Radiation

The railway carbody structure for commuter and suburban services in Japan is often made of austenitic stainless steel, which is used in the form of the thin metal sheets by cold rolling. It is difficult to observe the strain distribution around the weld zone, which is the critical area of the body structure strength. The objective of this study is to get the strain distribution in stainless steel around the weld zone. To observe the distribution, the strain scanning method by using high-energy synchrotron radiation was applied to the strain measurement of austenitic stainless steel. The transmission method was applied in order to observe internal weld zone. Using this method, we could measure the distribution from surface to inside of the weld zone. The specimen of lapped joint prepared by welding 2mm thick plates by laser weld method was used for measurement. This measurement provides the strain distribution of both residual strain and strain under loading. The result by this measurement shows strain distribution in the weld zone successfully. In addition, the different tendency between the distribution of residual strain and that of strain under loading made be clear. The full width of half maximums, FWHM, of measurement shows a difference between the tendency of measured value of weld zone and that of base material.

Fundamental Research for Forensic Characterization of Soil Samples by Using Instrumental Analysis

Soil can be one of the most important physical evidence in a criminal investigation which contributes to prove a linkage between the suspect and the crime scene. In this work, the validity of multiple instrumental analytical techniques for forensic soil identification was studied using 148 soil samples collected from the Tokyo metropolitan area. The samples were characterized by X-ray diffraction (XRD) analysis, X-ray fluorescence (XRF) analysis, magnetic susceptibility determination, scanning electron microscopy with an energy dispersive X-ray spectrometer (SEM-EDS) and high-energy synchrotron radiation X-ray fluorescence (SR-XRF) analysis. It was found that soil samples collected from railway stations and roadside dust showed higher magnetic susceptibilities (≧0.5×10-4 m3 kg-1 for 25% of the samples collected ) than those of soil samples collected from rivers, ponds, and lakes (<0.1×10-4 m3 kg-1 for 40% of the samples colleted). Microscopic examination of the soil samples revealed three kinds of characteristic spherules: i.e., transparent, white, and black particles. The SEM-EDS analyses of the spherule samples showed the following compositional characteristics. The transparent spherules exhibited two compositional types: Na-Ca-Si-O and Ba-Ti-Si-O types. On the other hand, black ones were either Fe-O or Si-Mg-O types and white ones were either Al-O or Sr-Al-O types. It was concluded that these six types of spherules were found at characteristic points and consequently, they can be used as forensic soil identification.

Influence of Dynamic Recrystallisation on Texture Formation in ECAP deformed Nickel

3N nickel has been deformed by equal channel angular pressing (ECAP) at 400°C up to 3 passes using route A. The texture with respect to position in the deformed billet, i.e. from top to bottom, has been measured with high-energy synchrotron radiation. It is characterized by texture components typical for simple shear in the intersection plane of the square-shaped 90° bent channel. Besides, an oblique cube component is observed. Orientation imaging microscopy clearly shows that this component is due to partial recrystallization. Intensities of the texture components as well as deviations from their ideal shear positions vary from the top to the bottom of the billet and with the number of passes. The change of the intensity of texture components and the texture gradient investigated is discussed. Special emphasis is put on the influence of dynamic recrystallization on texture and microstructure formation during ECAP of fcc metals.

Direct observation of oxygen stabilization in layered ferroelectric Bi3.25La0.75Ti3O12

Electron charge density distributions in layered ferroelectrics Bi4Ti3O12 (BiT) and Bi3.25La0.75Ti3O12 (BLT) are investigated by analyzing high-energy synchrotron-radiation powder diffraction data using the maximum entropy method/Rietveld method. BiT shows that chemical bonding resulting from orbital hybridization is established between Bi–O in the perovskite layer only along the a axis, whereas BLT exhibits isotropic chemical bonding of Bi∕La–O with a high electron density both along the a and b axes. High endurance to polarization fatigue reported for BLT films is suggested to originate from the stabilization of oxygen in the perovskite layer due to the isotropic chemical bonding of Bi∕La–O.

Electron Charge Density Study on Antiferroelectric Phase Transition in PbZrO3

Electron charge density distributions of PbZrO 3 both in the paraelectric and antiferroelectric phases are investigated at 520 and 100 K, respectively, by analyzing the high-energy synchrotron-radiation (SR) powder diffraction data utilizing the maximum entropy method (MEM)/Rietveld method. A clear evidence to show that the Pb atom in the paraelectric phase is disordered in the ⟨ 110⟩ directions and forms covalent bonds with the neighboring twelve O atoms is revealed. In the antiferroelectric phase, the Pb atoms are ordered alternately parallel and antiparallel to the direction, which allows the formation of strong covalent bonds on the shortened Pb─O bonds. Anisotropic thermal motion of the O atoms in the paraelectric phase is observed, which implies the rotation of ZrO 6 octahedra at the antiferroelectric phase transition.

Atomic-Scale Structure of Polymer-Route Si-C-O Fibers Observed by Synchrotron Radiation X-Ray Diffraction

The atomic scale structure of amorphous Si-C-O ceramics fibers produced from the pyrolysis of a polycarbosilane precursor has been investigated by X-ray diffraction using high-energy synchrotron radiation at SPring-8. First peak in the total correlation function T(r) of the amorphous and the heat-treated fibers is analyzed to consist of two contributions: Si-C (1.89 Å) and Si-O (1.61 Å) bonds. The coordination number of C and/or O around Si is about four. This suggests that the Si-C-O fibers basically have a network structure that consists of two tetrahedral units: SiC4 and SiO4. The local chemical and structural orders vary continuously in the materials from the disordered network structure of SiC4 and SiO4 tetrahedra (mixture of amorphous SiC and SiO2) to nanocrystals of SiC and SiO2, through the ternary Si-C-O solid solution which is believed to have an intermediate structure between the amorphous and crystalline states.