Wavelength Dispersive Electron Probe Microanalysis Research Articles

Experimental Phase Equilibria and Liquidus of CaO-Al2O3-SiO2-Na2O-B2O3 Slags Relevant to E-waste Processing

Ternary master slags based on the CaO-Al2O3-SiO2 system with CaO/SiO2 (C/S) ratio 0.3–1.0 were doped with 5–20 wt pct of anhydrous borax (Na2B4O7) to study the phase equilibria of the quinary CaO-Al2O3-SiO2-Na2O-B2O3 slag system within the temperature range 1050–1350 °C. This research uses the well-known method of high temperature equilibration of slags followed by rapid quenching. The quenched slag samples were examined using a Scanning Electron Microscope (SEM) and Wavelength Dispersive Electron Probe Microanalysis (WD-EPMA) technique to determine the structure and to analyse the chemistry of the phases in equilibrium. The primary phase of 15 slag compositions was identified and the liquidus temperature of the slags were determined within an uncertainty range of ±10–20 °C by using an iterative approach. Overall, the liquidus temperature of slags decreased with increasing borax content with the highest liquidus reduction observed in slags having a C/S ratio 0.3 and the lowest in the slag series with C/S ratio of 1.0. A comparative analysis of the effect of borax, Na2O and B2O3 on the liquidus temperature of slags is discussed. Results indicated that although borax reduces the liquidus of ternary CaO-Al2O3-SiO2 slags, the addition of B2O3 individually showed more prominent effects than borax in reducing the slag liquidus. Anorthite (CaO.Al2O3.2SiO2), pseudowollastonite (CaO.SiO2) and gehlenite (2CaO.Al2O3.SiO2) primary phases were identified.

From Stromboli ashes to corrensite by hydrothermal synthesis: Hydrogeological inputs into Mars history

The detection of mixed-layered clays is well known on Mars and evidences the presence of water on the planet. To understand the processes related to the formation of these mixed-layered clays on Mars, we performed a set of hydrothermal syntheses on basaltic ash of Stromboli volcano (Southern Italy), selected for its composition similar to Martian rocks. Syntheses were carried out by opportunely modulating the experimental conditions. Trials were performed at constant pH = 5, with pressure of 0.1–50 Mpa and temperatures ranging from 150 °C to 350 °C, and runs lasting from 5 to 31 days. In specific conditions described herein, corrensite crystals (mixed-layered clays) were produced. Optical microscope (OM), Powder X-Ray Diffraction (PXRD) and Scanning and Transmission Electron Microscopy, both combined with Energy Dispersive Spectroscopy (SEM/EDS; TEM/EDS), wavelength-dispersive electron probe microanalysis (WDS/EPMA), X-ray fluorescence (XRF), thermogravimetric and differential scanning calorimetry (TG/DSC), Fourier transform infrared spectroscopy (FTIR/ATR) and micro-Raman spectroscopy (μR) were used for a detailed mineralogical, chemical and morphological characterization before and after hydrothermal alteration. The findings that emerge point out that corrensite formed on Mars probably originated from the alteration of the basaltic rocks at a low grade of hydrothermal metamorphism in a Fe(II) enriched environment.

Crack-enhanced weathering in inscribed marble: a possible application in epigraphy

Abstract. Raman spectroscopy has been applied to check if there are detectible material differences beneath the inscribed and non-inscribed areas of marble-based written artefacts, which could be further used to visualize lost or hardly readable text via suitable mapping. As a case study, marble segments with ∼ 2000-year-old inscribed letters from Asia Minor (western Turkey) and marble gravestones with 66 ± 14-year-old inscriptions from the cemetery of Ohlsdorf (Hamburg, Germany) have been subjected to Raman spectroscopy, as well as to complementary X-ray diffraction, wavelength-dispersive electron probe microanalysis, and Fourier-transform infrared spectroscopy, to thoroughly study the effect of different environmental conditions, grain size, and inscription age on the nature and penetration depth of marble alteration. The results demonstrate that environmental conditions rule over the type of dominant weathering changes, which are carotenoid molecular inclusions produced by lichen and amorphous carbon for marbles from Hamburg and Asia Minor, respectively. The alteration is much stronger in medium- and coarse-grained than in fine-grained marble, but it is suppressed by letter colouring. In the absence of letter colouring, the weathering-related products in both ancient and modern engraved marbles are more abundant beneath than away from the engraved areas, and the penetration depth is larger due to the enhancement of fissures and micro-cracks around the inscribed areas. We show that the Raman intensity ratio between the strongest peak of the weathering-related product (ν(C=C) ∼ 1520 cm−1 for carotenoids or the G peak ∼ 1595 cm−1 for soot-like carbon) and the strongest peak of marble (CO3 stretching near 1087 cm−1) can serve as a quantitative marker to indirectly map the lateral distribution of cracks induced during the inscribing process and hence can potentially be used to trace lost text on vanished marble inscriptions. This approach can be applied to other rock types, but further studies are required to identify the corresponding autochthonous weathering-related products.

Ni-in-garnet geothermometry in mantle rocks: a high pressure experimental recalibration between 1100 and 1325\xa0\xb0C

The temperature-dependent exchange of Ni and Mg between garnet and olivine in mantle peridotite is an important geothermometer for determining temperature variations in the upper mantle and the diamond potential of kimberlites. Existing calibrations of the Ni-in-garnet geothermometer show considerable differences in estimated temperature above and below 1100 °C hindering its confident application. In this study, we present the results from new synthesis experiments conducted on a piston cylinder apparatus at 2.25–4.5 GPa and 1100–1325 °C. Our experimental approach was to equilibrate a Ni-free Cr-pyrope-rich garnet starting mixture made from sintered oxides with natural olivine capsules (Niolv ≅ 3000 ppm) to produce an experimental charge comprised entirely of peridotitic pyrope garnet with trace abundances of Ni (10–100 s of ppm). Experimental runs products were analysed by wave-length dispersive electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). We use the partition coefficient for the distribution of Ni between our garnet experimental charge and the olivine capsule left( {{text{lnD}}_{{{text{grt}}/{text{olv}}}}^{{{text{Ni}}}} ; frac{{{text{Ni}}_{{{text{grt}}}} }}{{{text{Ni}}_{{{text{olv}}}} }}} right), the Ca mole fraction in garnet ({mathrm{X}}_{mathrm{grt}}^{mathrm{Ca}}; Ca/(Ca + Fe + Mg)), and the Cr mole fraction in garnet ({mathrm{X}}_{mathrm{grt}}^{mathrm{Cr}}; Cr/(Cr + Al)) to develop a new formulation of the Ni-in-garnet geothermometer that performs more reliably on experimental and natural datasets than existing calibrations. Our updated Ni-in-garnet geothermometer is defined here as:T left(^circ{rm C} right)=frac{-8254.568}{left(left( {mathrm{X}}_{mathrm{grt}}^{mathrm{Ca}} times 3.023 right)+left({mathrm{X}}_{mathrm{grt}}^{mathrm{Cr}} times 2.307 right)+left({mathrm{lnD}}_{frac{mathrm{grt}}{mathrm{olv}}}^{mathrm{Ni}} - 2.639 right)right)}-273pm 55where {mathrm{D}}_{mathrm{grt}/mathrm{olv}}^{mathrm{Ni}}= frac{{mathrm{Ni}}_{mathrm{grt}}}{{mathrm{Ni}}_{mathrm{olv}}}, Ni is in ppm, {mathrm{X}}_{mathrm{grt}}^{mathrm{Ca}} = Ca/(Ca + Fe + Mg) in garnet, and {mathrm{X}}_{mathrm{grt}}^{mathrm{Cr}}= Cr/(Cr + Al) in garnet. Our updated Ni-in-garnet geothermometer can be applied to garnet peridotite xenoliths or monomineralic garnet xenocrysts derived from disaggregation of a peridotite source. Our calibration can be used as a single grain geothermometer by assuming an average mantle olivine Ni concentration of 3000 ppm. To maximise the reliability of temperature estimates made from our Ni-in-garnet geothermometer, we provide users with a data quality protocol method which can be applied to all garnet EPMA and LA-ICP-MS analyses prior to Ni-in-garnet geothermometry. The temperature uncertainty of our updated calibration has been rigorously propagated by incorporating all analytical and experimental uncertainties. We have found that our Ni-in-garnet temperature estimates have a maximum associated uncertainty of ± 55 °C. The improved performance of our updated calibration is demonstrated through its application to previously published experimental datasets and on natural, well-characterised garnet peridotite xenoliths from a variety of published datasets, including the diamondiferous Diavik and Ekati kimberlite pipes from the Lac de Gras kimberlite field, Canada. Our new calibration better aligns temperature estimates using the Ni-in-garnet geothermometer with those estimated by the widely used (Nimis and Taylor, Contrib Mineral Petrol 139:541–554, 2000) enstatite-in-clinopyroxene geothermometer, and confirms an improvement in performance of the new calibration relative to existing versions of the Ni-in-garnet geothermometer.

Solid-solubilities of grain-growth inhibitors in WC-Ni-based cemented carbides: experimental investigations and thermodynamic calculations

Cr3C2, TaC and VC are the most widely used grain growth inhibitors (GGIs) in cemented carbides. The inhibition effectiveness and the formation of brittle carbides by over-doping these GGIs are closely associated with their solubilities in the binder phase. A series of WC-Ni-based “model alloys” with high content of binder phase and different dopants of GGIs have been designed based on thermodynamic calculations and then prepared through conventional powder metallurgy method. The subsequent microstructures and the solubilities of GGIs in Ni binder phase were characterized by means of scanning electron microscopy (SEM) and wavelength-dispersive electron-probe microanalysis (WDS-EPMA), respectively. The thermodynamic description of the fcc phase (Ni binder phase) has been remodeled according to the presently obtained experimental data. A good agreement between experimental data and thermodynamic calculations can be obtained, which can provide a theoretical basis to the development of WC-Ni-based cemented carbides.

Characterisation and Performance Optimisation of WC-MC/M(C,N)-Co Hardmetals

WC-MC/M(C,N)-Co hardmetals with 10 wt% Co were prepared in undoped, as well as in either Cr- or V-doped form. The starting formulations contained 5 wt% TiC or 5% (TiC+TiN), the latter with two different TiC/TiN ratios, and 10 wt% (Ta,Nb)C. For each composition, a low-C grade (Ms ≈ 75%) and a high-C grade (Ms ≈ 88%) was adjusted by C or W addition, to end up with 18 different hardmetal formulations, prepared in an industrial process. Model alloys, MC and M(C,N) phases with a composition reflecting the composition of these phases in the hardmetal were prepared, too. A variety of data was collected: binder phase and hard phase compositions of model alloys by wavelength-dispersive electron-probe microanalysis (WDS-EPMA), liquid phase formation temperatures in model alloys with free C and eta by differential thermal analysis (DTA), respectively, thermal conductivities of MC and M(C,N) phases and hardmetals by laser-flash temperature conductivity and heat capacity measurements up to 950 °C, crystallite-size distribution by electron backscatter diffraction EBSD, hardness HV30, Palmqvist-Shetty fracture toughness KIC, Weibull evaluation of the transverse rupture strength (TRS), oxidation resistance in air as well as milling tests on coated hardmetals with Ti(C,N)/Al2O3 and (Ti,Al)N layers.

Quantitative measurement of olivine composition in three dimensions using helical-scan X-ray micro-tomography

Olivine is a key constituent in the silicate Earth; its composition and texture informs petrogenetic understanding of numerous rock types. Here we develop a quantitative and reproducible method to measure olivine composition in three dimensions without destructive analysis, meaning full textural context is maintained. The olivine solid solution between forsterite and fayalite was measured using a combination of three-dimensional (3D) X-ray imaging techniques, 2D backscattered electron imaging, and spot-analyses using wavelength-dispersive electron probe microanalysis. The linear attenuation coefficient of natural crystals across a range of forsterite content from ∼73–91 mol% were confirmed to scale linearly with composition using 53, 60, and 70 kV monochromatic beams at I12-JEEP beamline, Diamond Light Source utilizing the helical fly-scan acquisition. A polychromatic X-ray source was used to scan the same crystals, which yielded image contrast equivalent to measuring the mol% of forsterite with an accuracy of 3 mm domains within a large crystal of San Carlos forsterite that varies by ∼2 Fo mol%. This offers a solution to an outstanding question of inter-laboratory standardization, and also demonstrates the utility of 3D, non-destructive, chemical measurement. To our knowledge, this study is the first to describe the application of XMT to quantitative chemical measurement across a mineral solid solution. Our approach may be expanded to calculate the chemistry of other mineral systems in 3D, depending upon the number, chemistry, and density of end-members.

Complementary Characterization of Cu(In,Ga)Se₂ Thin-Film Photovoltaic Cells Using Secondary Ion Mass Spectrometry, Auger Electron Spectroscopy, and Atom Probe Tomography.

To enhance the conversion performance of solar cells, a quantitative and depth-resolved elemental analysis of photovoltaic thin films is required. In this study, we determined the average concentration of the major elements (Cu, In, Ga, and Se) in fabricated Cu(In,Ga)Se2 (CIGS) thin films, using inductively coupled plasma atomic emission spectroscopy, X-ray fluorescence, and wavelengthdispersive electron probe microanalysis. Depth profiling results for CIGS thin films with different cell efficiencies were obtained using secondary ion mass spectrometry and Auger electron spectroscopy to compare the atomic concentrations. Atom probe tomography, a characterization technique with sub-nanometer resolution, was used to obtain three-dimensional elemental mapping and the compositional distribution at the grain boundaries (GBs). GBs are identified by Na increment accompanied by Cu depletion and In enrichment. Segregation of Na atoms along the GB had a beneficial effect on cell performance. Comparative analyses of different CIGS absorber layers using various analytical techniques provide us with understanding of the compositional distributions and structures of high efficiency CIGS thin films in solar cells.

Medieval Gilding Technology of Historical Metal Threads Revealed by Electron Optical and Micro-Raman Spectroscopic Study of Focused Ion Beam-Milled Cross Sections.

Although gilt silver threads were widely used for decorating historical textiles, their manufacturing techniques have been elusive for centuries. Contemporary written sources give only limited, sometimes ambiguous information, and detailed cross-sectional study of the microscale soft noble metal objects has been hindered by sample preparation. In this work, to give a thorough characterization of historical gilt silver threads, nano- and microscale textural, chemical, and structural data on cross sections, prepared by focused ion beam milling, were collected, using various electron-optical methods (high-resolution scanning electron microscopy (SEM), wavelength-dispersive electron probe microanalysis (EPMA), electron backscattered diffraction (EBSD) combined with energy-dispersive electron probe microanalysis (EDX), transmission electron microscopy (TEM) combined with EDX, and micro-Raman spectroscopy. The thickness of the gold coating varied between 70-400 nm. Data reveal nano- and microscale metallurgy-related, gilding-related and corrosion-related inhomogeneities in the silver base. These inhomogeneities account for the limitations of surface analysis when tracking gilding methods of historical metal threads, and explain why chemical information has to be connected to 3D texture on submicrometre scale. The geometry and chemical composition (lack of mercury, copper) of the gold/silver interface prove that the ancient gilding technology was diffusion bonding. The observed differences in the copper content of the silver base of the different thread types suggest intentional technological choice. Among the examined textiles of different ages (13th-17th centuries) and provenances narrow technological variation has been found.

The Menengai Tuff: A 36 ka widespread tephra and its chronological relevance to Late Pleistocene human evolution in East Africa

Abstract The East African Rift preserves the world's richest Middle and Late Pleistocene (∼780–12 ka) geological, archaeological and paleontological archives relevant to the emergence of Homo sapiens . This region also provides unparalleled chronological control for many important sites through tephrochronology, the dating and correlation of volcanic ashes as widespread isochronous markers in the geological record. There are many well-characterized Pliocene-Early Pleistocene tephras that are widespread across East Africa. A comparable framework is lacking for the Middle and Late Pleistocene; a period characterized by spatially and temporally complex patterns of climate change, as well as the emergence of modern Homo sapiens and the dispersal of this species across and out of Africa. Unraveling relationships among these spatial and temporally complex phenomena requires a precise chronology. To this end we report the Menengai Tuff, a widespread volcanic ash produced by the large-scale caldera-forming eruption in Kenya and 40 Ar/ 39 Ar dated to 35.62 ± 0.26 ka. Geochemical characterization of 565 glass shards from 36 samples by wavelength-dispersive electron probe microanalysis show the Menengai Tuff was deposited over >115,000 km 2 and is found in the Baringo, Chalbi, Elmenteita, Nakuru, Olorgesailie, Turkana, and Victoria basins, all of which preserve rich Late Pleistocene paleoenvironmental and archaeological archives. Correlation and dating of the Menengai Tuff demonstrate that it is the most widespread tephra and largest eruption currently known from the Late Pleistocene of East Africa. As such, it is a valuable marker in establishing a Late Pleistocene chronology for paleoclimatic, archeological, and paleontological records relevant to the study of human evolution.

Solubilities of grain-growth inhibitors in WC-Co-based cemented carbides: Thermodynamic calculations compared to experimental data

Cr3C2, VC, TaC, NbC, ZrC and their certain combinations are commonly added to WC-Co-based cemented carbides as grain-growth inhibitors. The solubility of these grain-growth inhibitors in the binder phase is an important knowledge in the development of cemented carbides. Thermodynamic calculations have been carried out to design the alloy compositions of WC-Co-based model alloys with high Co contents. The calculations are compared to the data obtained on model alloys, which were characterised by means of X-ray diffraction (XRD), light-optical microscopy (LOM) and wavelength-dispersive electron-probe microanalysis (WDS-EPMA). Extensive thermodynamic calculations were performed and compared with the experimental data from our work and those reported in the literature. A good agreement between calculation and experiment thereby validates the accuracy of our established thermodynamic database of the cemented carbides.

A methodology for wavelength dispersive electron probe microanalysis of unpolished silicate minerals

Evaluation of mineral compositions is a widely used approach in resource exploration strategies where preparation time and cost may prove to be an important factor. In research institutes it is highly beneficial to determine the major element composition of minerals prior to their destructive analysis for trace elements and radiogenic isotopic ratios thus allowing a comprehensive interpretation of mineral petrogenesis. For the analysis of unique and small (submilligram) samples, avoiding sample loss is a key issue in ultimately producing high quality geochemical data. Consequently here we evaluate the precision and accuracy of electron probe microanalysis of unpolished garnet, olivine, orthopyroxene and clinopyroxene grains by comparison of analyses performed on polished thin sections of the same minerals. By utilizing a protocol that focuses on flat mineral surfaces, rejects analyses with low totals (<90%) and major element compositions, magnesium numbers and stoichiometry outside two standard deviation, results had on average a reproducibility of 1.3 times the relative standard deviation of the results of polished thin sections. Major element ratios are indistinguishable from the thin section results. For example, the Mg# for clinopyroxene and olivine is within 0.4% and for garnet within 1–1.5%. Individual analyses of minerals with flat surfaces such as clinopyroxene had a higher rate of success (73%) than minerals with a more variable surface topography such as conchoidally fractured garnet (40%), underlining that a flat topography is the controlling factor in EPMA analyses. These tests establish that accurate and reproducible EPMA analysis can be produced on unpolished minerals that are within error of conventional thin section analyses. The technique is predicted to be of particular use in diamond exploration strategies where knowledge of the geotherm beneath exploration areas is a key parameter. Integrated studies of composition and geochronology of mineral inclusions in diamonds have the potential to significantly improve the understanding of diamond formation processes and the imposed octahedral morphology of the inclusions mean that they have flat crystal faces, ideal for analysis using the proposed methodology.

Archaeometric analysis of vitreous material ornaments from the Villa di Villa site (Treviso, Italy)

The research focused on chemical and mineralogical analyses of eight vitreous material ornaments with a not well-defined chronology, coming from the protohistoric and Roman site of Villa di Villa in Cordignano–Colle Castelir (Treviso, north-eastern Italy). Eleven microsamples from the bodies and decorations of the ornaments underwent wavelength-dispersive electron probe microanalysis, scanning electron microscopy combined with energy dispersive spectrometry (EDS) and micro-Raman Spectroscopy. Non-invasive X-ray powder diffraction was performed on the surface of the ornaments. All vitreous materials were obtained using natron as flux except for one annular blue bead produced with mixed alkali plant ashes. The analyzed dark blue glasses are Co colored, only the pale blue melon bead faience is Cu colored. Opaque white and yellow glasses of two objects are opacified by Ca and Pb antimonates, respectively. The heterogeneous texture of some glasses is due to unreacted raw materials and/or newly formed crystals. The relationship between the Villa di Villa ornaments and coeval European/Mediterranean vitreous materials is also discussed. Composition, texture and morphological characteristics of the ornaments shed light on the different types of raw materials used and allow us to verify the main types of glass that occur during the great time span of life of the site and above all to answer to specific archaeological questions about possible chemical correlations between similar objects from the same or different SU. In two cases, the analytical data provide more detailed information about the ages of the ornaments.

Theoretical structures of the satellite and hypersatellite M-x-ray lines of uranium

The structure of satellite (additional vacancies in N and/or O shells) and hypersatellite (additional vacancies in M or M and N shells) Mα1,2 and Mβ1 lines in the x-ray spectra of heavy atoms can be explained precisely by taking into account the extensive multiconfiguration Dirac–Fock calculations. The presented results are a precursor for the reliable quantitative interpretation of a very complex origin structure of Mα1,2 and Mβ1 lines in various high-resolution x-ray spectra of heavy atoms induced by different light and heavy projectiles. Moreover, the intensities of the M-x-ray lines of uranium can be helpful in the application of x-ray measurements from UO2 as a reference material (virtual standard) for non-destructive wavelength-dispersive electron probe microanalysis.

Microbeam analysis of irradiated nuclear fuel

Microbeam analysis is widely used in the nuclear power industry. It is used to characterise the as-fabricated fuel, for routine post-irradiated examination and for research into the mechanisms of phenomena that limit the energy production of the fuel. The techniques most commonly used are wavelength-dispersive electron probe microanalysis, scanning electron microscopy and secondary ion mass spectrometry. Other microbeam analysis techniques that have been successfully applied to irradiated nuclear fuel are transmission and replica electron microscopy, X-ray fluorescence and micro X.-ray diffraction. Specific examples illustrating the past and present use of microbeam analysis in nuclear research establishments are presented with emphasis on the unique results they provide. As an aid to understanding, some basic facts about nuclear fuel rods and their irradiation are first given. This is followed by a description of features that set apart the microbeam analysis of high radioactive materials from standard practice.

WDX Studies on Ceramic Diffusion Barrier Layers of Metal Supported SOECs

AbstractSolid oxide electrolyser cells (SOECs) have great potential for efficient and economical production of hydrogen fuel. Element diffusion between the Ni‐cermet electrode and the metal substrate of metal supported cells (MSC) is a known problem in fuel cell and electrolysis technology. In order to hinder this unintentional mass transport, different ceramic diffusion barrier layers (DBLs) are included in recent cell design concepts. This paper is based on wavelength dispersive X‐ray fluorescence investigations of different SOEC and focuses on Fe, Cr and Ni diffusion between the metal grains of the cathode and the metal substrate. Due to the low detection limits and therefore high analytical sensitivity, wavelength dispersive electron probe microanalysis (EPMA) provides a precise method to determine element distribution, absolute element concentration and changes between the reference material and aged cells on a microstructural level by element mappings and concentration profiles. The results of this work show considerable concentration gradients in the metal grains caused by mass exchange during cell operation. Diffusion can be inhibited significantly by integrating different ceramic DBLs of doped LaCrO3‐type or doped LaMnO3‐type perovskite, either by vacuum plasma spraying (VPS) or physical vapour deposition technique (PVD).

Account of the background in wavelength dispersive X-ray electron probe microanalysis based on the simulation of bremsstrahlung X-radiation

The potentials of six approximation functions described in the literature and used to simulate bremsstrahlung X-radiation in electron probe microanalysis are analyzed within a uniform approach. An algorithm based on the use of wave spectra is proposed for determining the parameters of the functions. It is found that the calculated values of some parameters of approximation functions considerably differ from those presented by the authors of the functions. It is found that the quality of approximating bremsstrahlung X-radiation is strongly affected by the method of calculating the average atomic number of the sample and the corrections for matrix effects. In the wavelength range 0.1 ≤ λ ≤ 1.2 nm for atomic numbers 10 ≤ Z ≤ 83 and accelerating voltages 15 ≤ E0 ≤ 25 kV, the best function ensures background estimation with a relative standard deviation of 3–6%, which is comparable with the relative standard deviation of the direct background measurement in routine electron probe microanalysis. The use of the calculation method of the background account at λ > 1.2 nm is complicated because of the significant uncertainty of the absorption factor in the long-wavelength region for the majority of elements.

Solute redistribution during transient liquid phase bonding of IN738LC with BNi-3 interlayer

Redistribution of alloying elements in the transient liquid phase (TLP) bonding zone of IN738LC/BNi-3/IN738LC was studied to investigate microstructural evolution in this area. Wavelength dispersive spectrometry and electron probe microanalysis revealed that, during non-isothermal solidification in the TLP bonding zone, enrichment of residual liquid phase with the positive segregating elements caused formation of intermetallic in the bonding zone. Scanning electron microscopy observation indicated that the redistribution of alloying elements, between TLP bonding zone and base alloy, resulted in formation of a γ′ boundary layer, containing high density of fine γ′, around the bonding zone. Diffusion of γ′ promoting elements, from the base alloy inward the TLP zone, controlled the growth of this layer. Unlike TLP bonding at 1100–1150°C, isothermal solidification kinetic was reduced notably during TLP bonding at 1200–1250°C. Investigations demonstrated that the low isothermal solidification kinetic was not only due to the enrichment of liquid phase with the base alloying elements such as Ti and Zr, which was reported in the previous papers, but also the reduction of solid solubility limit of B in the base alloy contributed to the reduction of isothermal solidification kinetic.

Magnetic susceptibility and biotite composition of granitoids of Amritpur and adjoining regions, Kumaun Lesser Himalaya

Felsic magmatism in Amritpur and adjoining localities of Kumaun Lesser Himalaya is represented by Palaeoproterozoic (~1890 Ma) Bt-Ms granitoids and quartz feldspar porphyries, referred to as Amritpur granitoids (AG) and Amritpur porphyry (AP) respectively. The AG are porphyritic and equigranular as well, and extend from Suraijula (west) to Barhoan (east) in the Nainital district of Kumaun Lesser Himalaya. The Main Boundary Thrust (MBT) forms the southern boundary of AG, and quartzite-metabasalts association is exposed in the north. The equigranular variety of AG, referred to as Amritpur leucogranite (ALG) dominates over porphyritic ones, and is medium- to coarse-grained, hypidiomorphic, mainly composed of K-feldspar (perthite), quartz and plagioclase (sericite). Muscovite is present associated with biotite but varies in proportion ranging from rare to noticeable amount. The magnetic susceptibility (MS) measurements of AP and AG were carried out in the field on smooth rock surfaces using hand-held SM-20 magnetic susceptibility meter. The obtained MS value (SI unit) was further corrected according to the degree of the rock-surface unevenness. Primary biotites from ALG were analyzed by wavelength dispersive electron-probe microanalysis. Ferrous and ferric iron from total iron (FeO) of biotite was estimated following charge-balance procedures. The MS values of AP vary from 0.399 to 0.912×10 -3 SI unit with an average of 0.528×10-3 SI (N=17), which typically represent ilmenite series (χ ≤3.0×10 -3 SI) granite (Ishihara 1977). Medium- grained ALG measures relatively lesser MS values (χ= 0.003- 0.148×10 -3 SI) with an average of 0.062×10 -3 SI (N=55) compared to coarse-grained ALG which vary from 0.025 to 0.195×10 -3 SI with an average MS of 0.117×10-3 SI (N=18), both being related to ilmenite series granite. Coarse-grained gneissic AG, exposed at places, record the MS values ranging from 0.295 to 0.527×10 -3 SI with an average MS value of 0.379×10 -3 SI (N=26). Porphyritic AG, an older lithounit, are xenolith-bearing and xenolith-free, and their MS values range from 0.368 to 0.629×10-3 SI and from 0.142 to 0.247×10 -3 SI with average MS of 0.522×10 -3 SI (N=10) and 0.190×10 -3 SI (N=10) respectively. The observed MS variations of porphyritic AG appear related with xenolith incorporation, which might have slightly oxidized the porphyritic AG. The MS values of AP and AG including the ALG typically correspond to ilmenite series granites, and the noted MS variations may be related with their differing contents of ferromagnesian minerals, ilmenite and textural variations. The AG including the ALG are typically peraluminous (S-type) consistent with their nature similar to ilmenite series granites. About 60% of whole-rock data (N=13) of AP (Gupta et al. 1994; Nautiyal and Rawat 1990) are metaluminous (I-type) despite of their exclusively ilmenite series nature. In Japan nearly all the ilmenite series are I-type, and it has been observed that magnetite-/ilmenite-series classification is not exactly equivalent to the I-/S-type classification in terms of alumina saturation index (ASI). The ALG biotites have ΣX variation between 1.02 and 1.25 atoms in their structural formulae, which are dominantly contributed by potassium. The observed ΣX values more than one in ALG biotites may be due to the replacement of K by the elements Ba, Rb and Cs. Biotites of ALG plot into the field of primary biotite crystallized in felsic magma but scatter at and above the Ni-NiO buffer. However, presence of ilmenite and substantially low MS values (0.003-0.157×10 -3 SI) of ALG suggest the prevalence of elevated reducing conditions during the evolution of ALG magma. The ALG melt was further reduced at emplacement level as evident by the presence of graphite pods and patches hosted in the ALG near the contact with country- rocks. The biotites of ALG are ferri-biotites showing enrichment in siderophyllite component, which is commonly available in crustally-derived felsic melt. The ALG biotites in terms of MgO- FeO t

Analysis of Pu by Virtual-standard WDS-EPMA. Results of an interlaboratory round-robin test for wavelength-dispersive electron-probe microanalysis

Analysis of Pu by Virtual-standard WDS-EPMA. Results of an interlaboratory round-robin test for wavelength-dispersive electron-probe microanalysis