Search

AbstractThe distribution of U and Pu of a mixed-oxide fuel sample is analyzed by Raman spectroscopy and electron probe microanalysis, with the goal of comparing the distribution maps from the two techniques. Qualitatively, the maps reveal the same features of Pu-rich agglomerates and the near Pu-free UO2 matrix, and the differences between the derived absolute concentrations are within 10%. Differences are likely due to a shift in the Raman signal originating from the local stoichiometry variation or self-irradiation damage. [ABSTRACT FROM AUTHOR]

In this work, the phase equilibria of the binary Ag-In system were determined using electron probe microanalysis and differential scanning calorimetry on equilibrated alloys and diffusion couples. The compositions of the phase boundaries of solid phases that are highly scattered in the literature have been precisely determined. The temperatures of the invariant reaction ζ ⇄ γ + L and the polymorphic transformation ζ ⇄ γ are substantially lower than previously reported values. In addition, it was found that the In-rich ζ phase phase-separates after months of room-temperature aging. [ABSTRACT FROM AUTHOR]

Atacamite, empirical formula (Cu1.97Zn0.01)Cl0.94(OH)3.02, from the paleofumaroles of the monogenic volcano of Mount 1004, Tolbachik, Kamchatka, Russia, has been studied by thermal and electron microprobe analyses, X-ray powder diffraction, IR and Raman spectroscopy, and Calvet microcalorimetry. The thermal decomposition of atacamite was studied using X-ray diffraction and IR spectroscopy. The enthalpy of formation from elements for atacamite of the theoretical composition Cu2Cl(OH)3 (−810.2 ± 7.7 kJ/mol) was determined by melt dissolution calorimetry, and the Gibbs energy of formation (−657.0 ± 7.7 kJ/mol) was calculated. The stability of atacamite in the Cu–O–Cl–H system was thermodynamically modeled based on the obtained data, and the boundaries of its stability field were calculated under conditions of high alkalinity and high acidity of the mineral-forming medium. [ABSTRACT FROM AUTHOR]

The Ahetala granodiorite is located in the western section of the South Tianshan Orogenic Belt (STOB), which is of great significance regarding the dispute on the closing date of the South Tianshan Ocean (STO) and the tectonic evolution of STOB. To determine the tectonic setting and petrogenesis, the study of petrography, electron probe microanalysis (EPMA), LA-ICP-MS zircon U–Pb geochronology, and major and trace elements analyses are carried out for Ahetala granodiorite. Based on LA-ICP-MS U–Pb zircon dating, the granodiorite was emplaced at 282.1 ± 1.3 Ma (MSWD = 1.11). Geochemically, Ahetala granodiorite is characterized by metaluminous (A/CNK = 0.86–0.87), rich alkali (K2O + Na2O = 6.80–7.13), which belongs to high-K calc-alkaline I-type granite. They are enriched in LREE and depleted in HREE (LREE/HREE = 9.02–13.89) and exhibit insignificant Eu anomalies (δEu = 0.94–0.97). Ahetala granodiorite is enriched in large ion lithophile elements (e.g., K, Sr, Ba) and depleted in high field-strength elements (e.g., Ta, Ti, Nb, P). The Nb/Ta values (10.97–18.10), Zr/Hf values (39.41–40.19), and Mg# (54.87–56.02) of the granodiorite and the MgO content of biotites (13.42–14.16), the M value (M = Mg/(Mg + Fe2+)) of amphiboles (0.68–0.75), suggest that granodiorite originates from the crustal contamination of the mantle-derived magmas. Combined with regional geological background, previous research, and the nature of the Ahetala granodiorite, we suggest that Ahetala granodiorite was emplaced at a transitional stage of the volcanic arc (syn-collision) to post-collision setting and the South Tianshan Ocean was closed in the Early Permian. [ABSTRACT FROM AUTHOR]

Since the initial solute concentration distribution of the sinusoidal solution model shows a significant deviation from the actual concentration distribution of nickel-based single crystal (SX) superalloy dendrites, it is limited to calculate the diffusion coefficient of SX in the homogenization treatment. Therefore, this work proposes a new Gaussian solution model to calculate the diffusion coefficients and the diffusion activation energy of alloying elements in SX superalloy at high temperatures. The diffusion activation energies of W, Ta, and Ti elements in the studied alloy are consistent with the results from other works. This model could more accurately determine the diffusion coefficient of elements during the dendrite homogenization process of SX superalloys since it reflects actual physical processes. Moreover, it has the potential to use in various alloy systems and contributes to the formulation of effective homogenization treatments. • A new model is proposed to accurately determine the inter diffusion coefficient of single-crystal superalloys. • The model shows that a higher gradient of the diffusion chemical potential results in a higher final diffusion coefficient. • The results of the diffusion activation energy demonstrate the robustness of this model. [ABSTRACT FROM AUTHOR]

[Display omitted] • The LFC deposit belongs to the skarn-type polymetallic sulfide deposit. • A Comparative Study of the LFC Deposit and "Makeng-Type" Deposit Has Been Conducted. • Emphasizing the significance of disconformity between the Jinshe and Lindi Formations within the window areas of the thrust-nappe structure system in large iron deposit exploration. The Southwest Fujian Depression Belt is a prominent metallogenic zone for skarn-type iron polymetallic deposits in China, with the Longfengchang (LFC) sulfur polymetallic deposit representing a medium-scale, sulfide-dominated deposit in this region. This study conducted a detailed analysis of the LFC deposit, focusing on its mineralogy, mineral composition, and in-situ sulfur isotopes, alongside a comparative study with the "Makeng-type" deposit. The study aims to elucidate the genesis of the LFC deposit, its relationship with the "Makeng-type" deposit, and the factors underlying differences in dominant economic minerals and resource scale. The LFC deposit is hosted within the skarn above the fault contact zone between the Lindi Formation sandstone and the Chuanshan–Qixia Formation carbonate, with mineralization stages classified as skarn-magnetite, quartz-sulfide, and carbonate. LFC garnets are primarily composed of CaO, TFeO, and SiO 2 , with minor Al 2 O 3 and trace amounts of MgO and MnO, classifying them as distal exoskarn andradite. The presence of Mn3+ substituting for Fe3+ in garnet suggests that the ore-forming fluid during the garnet skarn stage was likely oxidizing and weakly acidic. LFC pyrites exhibit Co/Ni ratios primarily ranging from 1 to 10, decreasing from Py 1 to Py 3. In-situ sulfur isotope δ34S values range from −1.48 to 3.51 ‰, centering around 0 ‰, and increase from Py 1 to Py 3 , suggesting a magmatic-hydrothermal origin and a cooling metallogenic process. Thus, the LFC deposit is classified as a magmatic-hydrothermal skarn-type deposit, consistent with the genesis of "Makeng-type" deposits. The absence of the Jinshe Formation, and mantle-derived magma contribution, and less developed "Si-Ca" interface may explain the smaller scale and different mineralization type in the LFC deposit compared to the "Makeng-type" deposit. The key prospecting area for large iron-sulfur polymetallic deposits in the Southwest Fujian Depression Belt should feature a nappe structural window, well-preserved Jinshe Formation, developed "Si-Ca" interface, Yanshanian high-K calc-alkaline to shoshonitic intrusions, and coeval mantle-derived magma. [ABSTRACT FROM AUTHOR]

The structural properties and composition of metamict minerals, namely allanite, chevkinite, and britholite, occurring as inclusions in allanite from feldspar syenites of the Velyka Vyska massif (Korsun-Novomyrhorod pluton, Ukrainian Shield) were investigated by X-ray diffraction and electron probe microanalysis (EPMA). The age of the syenites is 1.7-1.8 Ga, which corresponds to their formation ages within the Ukrainian Shield. X-ray analysis shows that of the original samples of chevkinite and allanite give a broad diffraction peak between 16- 28° 2Θ as well as Bragg reflections in the region of the most intense reflections of semimetamict allanite and britholite, indicating the metamict state of chevkinite and the semimetamict state of allanite. The content of radioactive Th found in the chevkinite (0.25-0.33 apfu) is higher compared to its amount in allanite (0.024- 0.033 apfu). Calculated unit-cell parameters of the chevkinite and allanite samples showed that their structures underwent significant changes after annealing. There is a slight distortion of the chevkinite unit cell related to a decrease in the a and an increase in b and c edges. A decrease in b and the increase in c in the allanite is caused by a redistribution of cations in the structure and an oxidation of iron, Fe2+ → Fe3+c, during heating. Thereby the stability of the allanite structure decreases and it ultimately breaks down. The structural sites A and A2 in chevkinite and allanite are mainly occupied by REEs of the cerium group. The amount of Y is minor. The substitution mechanism A2(REE)3+ + M3M2+ → A2Ca2+ + M3M3+(allanite) and M2Fe3+ + M3,4Ti4+ ↔ M2Fe2+ + + M3,4Nb5+ (chevkinite) occur. The M2 site in the structure of chevkinite and M3 in allanite contain more Fe2+ than Fe3+. This leads to a weakening of the bonds in their structures, and a stepwise breakdown and partial or total metamictization of their structures. The britholite inclusions in allanite belong to the Y variety. They were probably formed much later than allanite and chevkinite in the Velyka Vyska massif. According to the EPMA results, namely BSE-images and REE content determinations, allanite and chevkinite formed almost simultaneously. [ABSTRACT FROM AUTHOR]

Abstract Beryl is usually found in granite-pegmatite systems. The addition of chromophore elements (V, Cr, Mn, Fe) into the crystalline structure favors color changes in beryl and thus generates some of the world’s expensive gems such as emerald, morganite, heliodor and aquamarine. The Massangana polyphasic batholith is a well-known cassiterite, wolframite and gems deposit in the Rondônia state. These metals and blue-gems (topaz and aquamarine) are located in feldspar-rich pegmatite granite bodies. The aquamarine crystals show color ranging from light- to medium-blue and display concentric growth zones. Electron-probe microanalyses revealed that the Fe is the main chromophore element, occupying the octahedral Al-site, while Na had an important role in the charge balance, inserted in the channel sites together with H2O. The irregular supply of Fe and Na during the nucleation and growth of aquamarine was the main cause for the color change. A fluid inclusion study indicated that the aquamarine growth under an aqueous fluid system (H2O-NaCl), with low salinity, low density and total homogenization temperature between 243º-315º C, is compatible with final temperatures in the pegmatite pocket zone.

The Ahetala granodiorite is located in the western section of the South Tianshan Orogenic Belt (STOB), which is of great significance regarding the dispute on the closing date of the South Tianshan Ocean (STO) and the tectonic evolution of STOB. To determine the tectonic setting and petrogenesis, the study of petrography, electron probe microanalysis (EPMA), LA-ICP-MS zircon U–Pb geochronology, and major and trace elements analyses are carried out for Ahetala granodiorite. Based on LA-ICP-MS U–Pb zircon dating, the granodiorite was emplaced at 282.1 ± 1.3 Ma (MSWD = 1.11). Geochemically, Ahetala granodiorite is characterized by metaluminous (A/CNK = 0.86–0.87), rich alkali (K2O + Na2O = 6.80–7.13), which belongs to high-K calc-alkaline I-type granite. They are enriched in LREE and depleted in HREE (LREE/HREE = 9.02–13.89) and exhibit insignificant Eu anomalies (δEu = 0.94–0.97). Ahetala granodiorite is enriched in large ion lithophile elements (e.g., K, Sr, Ba) and depleted in high field-strength elements (e.g., Ta, Ti, Nb, P). The Nb/Ta values (10.97–18.10), Zr/Hf values (39.41–40.19), and Mg# (54.87–56.02) of the granodiorite and the MgO content of biotites (13.42–14.16), the M value (M = Mg/(Mg + Fe2+)) of amphiboles (0.68–0.75), suggest that granodiorite originates from the crustal contamination of the mantle-derived magmas. Combined with regional geological background, previous research, and the nature of the Ahetala granodiorite, we suggest that Ahetala granodiorite was emplaced at a transitional stage of the volcanic arc (syn-collision) to post-collision setting and the South Tianshan Ocean was closed in the Early Permian.

With the depletion of high-grade ores, beneficiation of valuable minerals from mineral processing tailings attracts attentions of mining companies and researchers. Recovery of valuable sulfide minerals by flotation from the tailing of an iron-copper mine in central China was investigated in this paper. The surface oxidation status of sulfide minerals is an important factor influencing their flotation properties. Electron probe microanalyzer (EPMA) equipped with wavelength dispersive X-ray spectrometer (WDS) is an effective apparatus for characterizing solid surface (interface), which can analyze the composition and element distribution on the surfaces of sulfide minerals so as to understand their oxidation status. EPMA-WDS was employed to analyze the phenomenon responsible for the low flotation recovery of chalcopyrite and pyrite in this tailing. The research methodology is a useful reference for further work in the field of sulfide mineral surface analysis. [ABSTRACT FROM AUTHOR]

The sequence of coastal and river sands of Pleistocene to Holocene age at the north head of the Waikato River is ~80-m thick; the sands are located in a fault-angle depression at the southern end of the Awhitu Peninsula, a 40-km-long coastal sand barrier. The sequence at Waikato North Head (WNH) consists of three main formations: Awhitu Sands, Hood Sands and Mitiwai Sands. The Waiuku Black Sand member of the Hood Sands and the Entrican Sand member of the Mitiwai Sands contain titanomagnetite-rich dune sands, which are currently mined by New Zealand Steel and constitute a giant placer deposit that has a total resource of ~90 Mt Fe. A tephra at the top of the Awhitu Sands is correlated with the ~1000 ka Waiuku (Potaka) tephra. The Mitiwai Sands overlie the 1.85 ka Taupo Pumice. Comparison of electron probe microanalyses (EPMA) of titanomagnetites in heavy mineral separates of surface and drill-hole samples indicated that the bulk of the titanomagnetite in the Waiuku Black sand and the Entrican Sand is derived from andesitic rocks of the Taranaki Volcanoes 220 km to the south. The Waiuku Black Sand may correlate with an influx of andesitic clasts and mafic minerals in the cover beds of the ~400 ka Ararata Terrace in south Taranaki. There is also a contribution of titanomagnetite and minor ilmenite from the ignimbrites of the Taupo Volcanic Zone (TVZ), particularly in the Lower Hood and Entrican sands. Automated mineralogy data collected on selected sand samples contain silicate and resistate minerals that indicate other potential sources in addition to the Taranaki andesites and TVZ ignimbrites. Minor olivine was likely derived from the late Pleistocene basalts of the South Auckland volcanic field, whereas almandine and epidote were likely sourced from metasedimentary rocks of the Murihiku and Waipapa terranes. The formation of the giant placer at WNH was a multistage process involving (1) a supply of titanomagnetite-bearing sand eroded from the late Pleistocene–Holocene andesites of the Taranaki volcanoes that was transported northwards along the coast by the prevailing longshore drift; (2) concentration of titanomagnetite by wave action on beach faces and collection in a coastal embayment on the northern side of a headland of basement rocks at Port Waikato; (3) further concentration by wind action into dune sands during interglacial low sea levels; and (4) preservation by coeval subsidence in a fault-angle depression on the down-thrown north side of the Waikato Fault. [ABSTRACT FROM AUTHOR]

The mining waste in Al-Amar gold mine is 150 kg a year due to leakage in the extraction process. Studying the textures of gold deposits can be helpful to improve the process of gold extraction. The present work aimed to study the texture, structure, and composition of gold deposits that have different textures and structures using Scanning Electron Microscope (SEM), Electron probe microanalysis (EPMA), and Micro X-ray Fluorescence (µXRF). The ore minerals at different gold deposits were determined and these are pyrite, chalcopyrite, sphalerite, galena, and silica. The contents of Si and Zn in some specific areas are highly indicated to silica and sphalerite minerals, respectively. Additionally, the high contents of Fe and S, as well as some Cu, confirm the presence of pyrite and chalcopyrite minerals. The µXRF technique was used for elemental mapping of S, Si, Ca, Ti, Mn, Fe, Cu, Zn, Pb, and Au. The spectral interference between Zn-Kβ and Au-Lα was found at different pixels and the Au-Lβ was free from interference and used for following the gold in the samples under investigation. The positive correlation between the Au and the elements Zn, Fe, Pb, and Si indicates the existence of the Au element in different minerals as an invisible specks. [ABSTRACT FROM AUTHOR]

The Mg-rich phase equilibria of the Mg-Y-Zn system at 500 °C were investigated with equilibrated alloys, by means of electron probe microanalysis and x-ray diffraction. A partial isothermal section of < 34 at.% Y and < 50 at.% Zn was constructed and an extended section of < 50 at.% Y was produced by integrating our previous results in the Zn-rich region. Following the previous finding of seven ternary phases (τ1 to τ7) in the Zn-rich region, seven more ternary phases (τ8 to τ14) were found in the Mg-rich region in the present work. With the systematic composition measurement and XRD analysis, six of them (τ8 to τ13) were determined to be the so-called LPSO phases. They are very close to one another in composition and located approximately along the line of Y/Zn ratio = 4/3. τ8 is believed to be X-Mg12YZn (14H), τ9 to be Mg10ZnY (18R) and τ13 to be 10H. [ABSTRACT FROM AUTHOR]

More than hundred diffusion couples between p- and n-type skutterudites and various materials were prepared and interaction zones were investigated after heat treatment at 600 °C for 1100 h. The constitution of reaction/diffusion zones was discussed in terms of: (a) atom site preference in the skutterudite lattice, (b) phase equilibria in multicomponent systems and (c) particularities of the crystal structure of intermediate phases. It could be shown that phase composition and thermo-mechanical properties of bonding can be engineered by chemical substitution. The results obtained allowed the determination of several necessary criteria for the development of chemically and mechanically stable diffusion barriers/couples for skutterudite based thermoelectric (TE) modules. [ABSTRACT FROM AUTHOR]

Beryl is usually found in granite-pegmatite systems. The addition of chromophore elements (V, Cr, Mn, Fe) into the crystalline structure favors color changes in beryl and thus generates some of the world's expensive gems such as emerald, morganite, heliodor and aquamarine. The Massangana polyphasic batholith is a well-known cassiterite, wolframite and gems deposit in the Rondônia state. These metals and blue-gems (topaz and aquamarine) are located in feldspar-rich pegmatite granite bodies. The aquamarine crystals show color ranging from light- to medium-blue and display concentric growth zones. Electron-probe microanalyses revealed that the Fe is the main chromophore element, occupying the octahedral Al-site, while Na had an important role in the charge balance, inserted in the channel sites together with H2O. The irregular supply of Fe and Na during the nucleation and growth of aquamarine was the main cause for the color change. A fluid inclusion study indicated that the aquamarine growth under an aqueous fluid system (H2O-NaCl), with low salinity, low density and total homogenization temperature between 243o-315o C, is compatible with final temperatures in the pegmatite pocket zone. [ABSTRACT FROM AUTHOR]

Copyright of Geochimica Brasiliensis is the property of Sociedade Brasileira de Geoquimica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The phase equilibria at 500 °C of the Mg–Nd–Zn system in the region of 0–50 at.% Nd were investigated by combining the electron probe microanalysis (EPMA) and X-ray diffraction (XRD) of the equilibrated alloys. The partial isothermal section was constructed. Eight ternary phases (τ 1 to τ 6 , τ 8 and T-NdMg 12) were found at 500 °C. Among them, τ 8 is the newly found ternary compound. T-NdMg 12 is the Zn-stabilized Mn l2 Th-type NdMg 12 phase. Its composition range was measured to be Nd 7.6-7.7 Mg 84.5-88.7 Zn 3.7-7.8. The homogeneity ranges of the seven ternary compounds (τ 1 to τ 6 and τ 8) were well determined. The solubilities of the third elements in the binary compounds of the three binary systems were also well measured. The lattice parameters of the τ 1 , τ 2 and τ 5 phases were determined to be a = 0.9709 (3) nm/ b = 1.1253 (4) nm/ c = 0.9545 (3) nm at Nd 7.8 Mg 57.0 Zn 35.2 (τ 1), a = 1.46234 (1) nm/ c = 0.8706 (1) nm at Nd 7.1 Mg 28.5 Zn 64.4 (τ 2) and a = 2.0883 (2) nm at Nd 16.7 Mg 18.5 Zn 64.8 (τ 5), respectively. • Isothermal section at 500 °C over the range below 50 at.%Nd was constructed. • Composition ranges of eight ternary phases (τ 1 to τ 6 , τ 8 and T-NdMg 12) were determined. • Lattice parameters of the τ 1 , τ 2 , τ 5 and T-NdMg 12 were calculated with fine XRD patterns. • Solubility of the third elements in binary phases was well measured. [ABSTRACT FROM AUTHOR]

Basic oxygen furnace (BOF) slag accounts for the majority of all residual materials produced during steelmaking and may typically contain certain transition metals. Vanadium, in particular, came into focus in recent years because of its potential environmental toxicity as well as its economic value. This study addresses the vanadium chemistry in BOF slags to better understand its recovery and save handling of the waste stream. The experimental results from the electron probe microanalysis (EPMA) study show that vanadium is preferably incorporated in calcium orthosilicate-like compounds (COS), with two variations occurring, a low vanadium COS (COS-Si) (approx. 1 wt.%), and a high vanadium COS (COS-V) (up to 18 wt.%). Additionally, vanadium is incorporated in dicalcium ferrite-like compounds (DFS) with an average amount of 3 wt.%. Using powder x-ray diffraction analysis (PXRD), EPMA, and virtual component models, stoichiometric formulas of the main vanadium-bearing phases were postulated. The stoichiometries give an estimate of the oxidation states of vanadium in the respective hosts. According to these results, trivalent vanadium is incorporated on the Fe-position in dicalcium ferrite solid solution (DFS), and V4+ and V5+ are incorporated on the Si-position of the COS.

In this paper we report the development of a new method for the evaluation of thin films mass thickness and composition based on the Energy Dispersive X-Ray Spectroscopy (EDS). The method exploits the theoretical calculation of the in-depth characteristic X-ray generation distribution function (ϕ(ρz)) in multilayer samples, where ϕ(ρz) is obtained by the numerical solution of the electron transport equation. Once the substrate composition in known, this method gives reliable measurements without the need of a reference sample and/or multiple voltage acquisitions. The electron transport model is derived from the Boltzmann transport equation and it exploits the most updated and reliable physical parameters in order to obtain an accurate description of the phenomenon. The method for the calculation of film mass thickness and composition is validated with benchmarks from standard techniques. In addition, a model uncertainty and sensitivity analysis is carried out and it indicates that the mass thickness accuracy is of the order of 10 μg / cm 2, which is comparable to the nuclear standard techniques resolution. We show the technique peculiarities in one example model: two-dimensional mass thickness and composition profiles are obtained for a ultra-low density, high roughness, nanostructured film. Unlabelled Image • Theoretical model for the calculation of characteristic X-ray generation function • Fast and reference-free measurements of thin films mass thickness and composition • Capability of thin films mass thickness and composition mapping • Characterization of nanostructured, ultralow density and high-roughness film [ABSTRACT FROM AUTHOR]

The correlation between microstructure and magnetic properties of 2:17 SmCo commercial magnets 32 H and 32 L is studied. The 32 H magnet with high coercivity has an excellent ($00l$) orientation texture, and its magnetic properties are (BH) $_{\mathrm {max}}= 29.47$ MGOe, $B_{\mathrm {r}} = 11.20$ kG, and $H_{\mathrm {cj}} = 29.45$ kOe. The magnetic properties of the 32 L magnet with low coercivity are (BH) $_{\mathrm {max}}= 29.28$ MGOe, $B_{\mathrm {r}} = 11.40$ kG, and $H_{\mathrm {cj}} = 9.829$ kOe. The electron probe microanalysis results show that a Cu-lean grain boundary region is obvious in the 32 H magnet, which affects the squareness of the demagnetization curve. The transmission electron microscope result shows that the cell size and cell boundary thickness of high and low coercivity magnets are 129.32 and 9.83, and 90.94 and 7.87 nm, respectively. But the cell structure of the 32 H magnet is more complete and clearer than that of the 32 L magnet. The difference of the Cu concentration between the cell boundary phase and cell phase in the 32 H magnet is bigger than that of the 32 L magnet, which is really responsible for the high coercivity. [ABSTRACT FROM AUTHOR]

High temperature corrosion of a Pt-30 wt.% Rh alloy in a phosphorizing gas was isothermally investigated at 1285 K using a gas switching technique. Diffusion of P into the alloy created an outer layer of Pt-rich liquid and blocky (Pt, Rh)2P precipitates along with an inner layer of fcc and (Pt, Rh)2P plates in a cellular microstructure. Concentration profiles measured by SEM-WDS and EPMA across the layers at room temperature showed that there were three fcc phases: first was a 12 at.% Rh phase in the outer layer; second was a 37 at.% Rh phase in the cellular microstructure; and third was the initial 43 at.% Rh alloy. Also, the EPMA data registered approximately 0.1 at.% P in fcc of these layers. Based on the surrounding binary phase diagrams and the experimental data obtained in this study, a partial Pt-Rh-P phase diagram was constructed. A diffusion path for the corrosion microstructure was drawn on the partial phase diagram to help develop a step by step model for how the microstructure evolved. Growth kinetics of the inner layer were used to calculate a P diffusivity of about 10−12 m2/s in the Pt-Rh alloy at 1285 K, suggesting rapid diffusion by either an interstitial or interstitialcy mechanism. [ABSTRACT FROM AUTHOR]

Lithium aluminum oxide has previously been identified to be a suitable compound to recover lithium (Li) from Li-ion battery recycling slags. Its formation is hampered in the presence of high concentrations of manganese (9 wt.% MnO2). In this study, mock-up slags of the system Li2O-CaO-SiO2-Al2O3-MgO-MnOx with up to 17 mol% MnO2-content were prepared. The manganese (Mn)-bearing phases were characterized with inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray diffraction (XRD), electron probe microanalysis (EPMA), and X-ray absorption near edge structure analysis (XANES). The XRD results confirm the decrease of LiAlO2 phases from Mn-poor slags (7 mol% MnO2) to Mn-rich slags (17 mol% MnO2). The Mn-rich grains are predominantly present as idiomorphic and relatively large (>50 µm) crystals. XRD, EPMA and XANES suggest that manganese is present in the form of a spinel solid solution. The absence of light elements besides Li and O allowed to estimate the Li content in the Mn-rich grain, and to determine a generic stoichiometry of the spinel solid solution, i.e., (Li(2x)Mn2+(1−x))1+x(Al(2−z),Mn3+z)O4. The coefficients x and z were determined at several locations of the grain. It is shown that the aluminum concentration decreases, while the manganese concentration increases from the start (x: 0.27; z: 0.54) to the end (x: 0.34; z: 1.55) of the crystallization.

Abstract The spatial distribution of heat producing elements (K, U, and Th) in the continental crust has long-term implications for the thermal and physical evolution of orogens. Heat producing elements, in particular Th, are most abundant in metasedimentary rock types. As such, these rock types have a significant control on the spatial distribution of heat production in the crust. The major host of the heat producing element thorium in pelitic metasedimentary rocks is the REE–Th phosphate monazite. We present in-field gamma ray spectrometry (in-field GRS) data integrated with grain-scale electron probe microanalysis data to reveal grain to terrane scale links in thorium distribution. In-field GRS data shows that thorium is not depleted in granulite facies residual rocks that have lost melt with respect to their subsolidus counterparts. Concurrently, the bulk thorium budget of monazite is approximately uniform within samples and if anything increases with increasing metamorphic grade. Monazite average grain size increases with metamorphic grade and prograde cores are largely preserved in granulite facies samples. Thorium is preserved in residual metasediments after melting and melt loss implying that even when melting and melt extraction is efficient it does not strip Th from granulite facies rocks. Highlights • Th preserved in granulite facies residue at both outcrop and micro-scales. • Prograde monazite zoning retained after granulite facies metamorphism and melt loss. • Abundance and total Th contained in monazite increases with metamorphic grade. [ABSTRACT FROM AUTHOR]

The iron oxidation state in silicate melts is important for understanding their physical properties, although it is most often used to estimate the oxygen fugacity of magmatic systems. Often high spatial resolution analyses are required, yet the available techniques, such as μrXANES and μMössbauer, require synchrotron access. The flank method is an electron probe technique with the potential to measure Fe oxidation state at high spatial resolution but requires careful method development to reduce errors related to sample damage, especially for hydrous glasses. The intensity ratios derived from measurements on the flanks of FeLα and FeLβ X-rays (FeLβf/FeLαf) over a time interval (time-dependent ratio flank method) can be extrapolated to their initial values at the onset of analysis. We have developed and calibrated this new method using silicate glasses with a wide range of compositions (43–78 wt% SiO2, 0–10 wt% H2O, and 2–18 wt% FeOT, which is all Fe reported as FeO), including 68 glasses with known Fe oxidation state. The Fe oxidation state (Fe2+/FeT) of hydrous (0–4 wt% H2O) basaltic (43–56 wt% SiO2) and peralkaline (70–76 wt% SiO2) glasses with FeOT > 5 wt% can be quantified with a precision of ±0.03 (10 wt% FeOT and 0.5 Fe2+/FeT) and accuracy of ±0.1. We find basaltic and peralkaline glasses each require a different calibration curve and analysis at different spatial resolutions (~20 and ~60 μm diameter regions, respectively). A further 49 synthetic glasses were used to investigate the compositional controls on redox changes during electron beam irradiation, where we found that the direction of redox change is sensitive to glass composition. Anhydrous alkali-poor glasses become reduced during analysis, while hydrous and/or alkali-rich glasses become oxidized by the formation of magnetite nanolites identified using Raman spectroscopy. The rate of reduction is controlled by the initial oxidation state, whereas the rate of oxidation is controlled by SiO2, Fe, and H2O content. [ABSTRACT FROM AUTHOR]

Quantitative electron probe microanalysis (EPMA) of trace elements using wavelength dispersive spectrometers (WDS) requires high probe current and/or accelerating voltage and long X-ray sampling times to measure weak X-ray signals from target materials. The X-ray count rate of a standard material is extremely high when measured under the same conditions. Consequently, the accuracy of the dead time correction becomes a significant issue for quantification. Accurate dead time correction requires an exact knowledge of the X-ray counting system, including the behavior of the proportional counter and electronic circuits. Each spectrometer has a specific dead time that depends on factors such as electronic circuit design, counter bias, and X-ray energies. The dead time also changes with aging degradation. A pseudo-fixed dead time correction circuit with non-extendable approximation is described that prevents systematic errors in quantitative EPMA caused by inappropriate dead time corrections. The circuit, which is added to the output of the single channel analyzer, includes one extendable and two non-extendable dead time generators with dead times of 0.68 μs, 1.08 μs, and 1.92 μs, respectively. The behavior of the whole system can be treated as non-extendable for most applications, with a dead time of approximately 2.01 μs. The pseudo-fixed dead time circuit suppresses systematic error of the dead time correction to 0.6% or less when the original dead time is between 0.8–2.0 μs and the true X-ray count rate is < 200 kcps. This makes it possible to perform accurate dead time corrections without periodic measurement of the dead time throughout the life of the proportional counter by implementing a high-precision crystal oscillator in the system. [ABSTRACT FROM AUTHOR]

Diffusion behavior of Ni during high temperature co-sintering was quantitatively investigated for anode-supported solid oxide fuel cells (SOFCs) that had BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3− δ (BZCYYb) proton-conducting electrolyte and NiO-BZCYYb anode. Although diffused Ni in such SOFCs effectively acts as a sintering aid to densify the BZCYYb electrolyte layer, it often negatively affects the electrolyte conductivity. In the present study, field emission electron probe microanalysis (with wavelength dispersive X-ray spectroscopy) clearly revealed that Ni diffused into the BZCYYb electrolyte layer, and that the amount of diffused Ni increased with increasing co-sintering temperature. In particular, relatively high Ni concentration within the electrolyte layer was observed near the electrolyte/anode interface, e.g., approximately 1.5 and 2.8 wt% at co-sintering temperature of 1300 and 1400 °C, respectively. Electrochemical measurements showed that, compared with the lower co-sintering temperatures (1300–1350 °C), the highest co-sintering temperature (1400 °C) led to the highest ohmic resistance because of lower electrolyte conductivity. These results suggest that high co-sintering temperature causes excessive Ni diffusion into the BZCYYb electrolyte layer, thus degrading the intrinsic electrolyte conductivity and consequently degrading the SOFC performance. [ABSTRACT FROM AUTHOR]

The paper summarizes the irradiation test and post-irradiation examination (PIE) data for the U-Mo low-enriched fuel that was irradiated in the MIR reactor under the RERTR Program. The PIE data were analyzed for both full-size fuel rods and mini-rods with atomized powder dispersed in Al matrix as well as with additions of 2%, 5% and 13% of silicon in the matrix and ZrN protective coating on the fuel particles. The full-size fuel rods were irradiated up to an average burnup of ∼ 60%235U; the mini-rods were irradiated to an average burnup of ∼ 85%235U. The presented data show a significant increase of the void fraction in the U-Mo alloy as the U-235 burnup rises from ∼ 40% up to ∼ 85%. The effect of irradiation test conditions and U-235 burnup were analyzed with regard to the formation of an interaction layer between the matrix and fuel particles as well as generation of porosity in the U-Mo alloy. Shown here are changes in distribution of U fission products as the U-235 burnup increases from ∼ 40% up to ∼ 85%.

The phase equilibria at 600 °C of the Y -Zn -Zr system were determined via investigating the reaction of Y-Zr alloy with Zn vapor and the equilibrated ternary alloys, by means of the electron probe microanalyses and x-ray diffraction. Two ternary phases, which are denoted as τ and τ, were found at 600 °C. The τ phase was deduced to have a triclinic structure. It has a homogeneity range of YZnZr and is located approximately between ZrZn and YZn. The τ phase was determined to have a homogeneity range of YZnZr (in at.%). The solubility of Zr in YZn was measured to be up to 10.4 at.% Zr. Thirteen three-phase equilibria were well determined. Six of them involving the τ or τ were found. The isothermal section at 600 °C was constructed over the entire composition range of the Y-Zn-Zr system. [ABSTRACT FROM AUTHOR]

Previous studies on the provenance of titanomagnetite-rich ironsands on the west coast of the North Island, New Zealand, have suggested that the main source is from erosion of andesitic volcanic rocks of the Taranaki volcanoes, with a lesser contribution from ignimbrites of the Taupo Volcanic Zone (TVZ) in, and north of, the Waikato North Head ironsand deposit. Here, we compare the results of electron probe microanalysis of titanomagnetite grains in samples of coastal and river sands (sinks), with a dataset (compiled from the published literature) of analyses of titanomagnetite in volcanic rocks erupted from Mt. Taranaki and TVZ volcanoes (potential sources). A principal components analysis was conducted on a five element (MgO, Al 2 O 3 , TiO 2 , MnO, FeO) dataset of Fe-Ti oxide compositions to identify groupings in multivariate space. The composition of titanomagnetites in the sinks from Whanganui to Waikawau Beach (southern sector) are similar to those of Mt. Taranaki andesites as sampled in the published literature; minor contributions from both Ruapehu andesites and TVZ ignimbrites are also present. The composition of titanomagnetites in the sinks at both Waikato North Head deposit and in the ironsands from Taharoa to Muriwai Beach (northern sector) are consistent with a composition of titanomagnetites that is present in the rivers that drain the Taranaki volcanoes and their ring plain debris avalanche and lahar deposits, but not a composition that is represented in the literature for Mt. Taranaki volcanic rocks. A minor proportion of the titanomagnetite grains in the Waikato North Head ironsand deposit and the coastal ironsands from Port Waikato north to Muriwai Beach appear to be sourced from ignimbrites of the TVZ. [ABSTRACT FROM AUTHOR]

Hydrocarbon contamination introduced during point, line and map analyses in a field emission electron probe microanalysis (FE-EPMA) was investigated to enable reliable quantitative analysis of trace amounts of carbon in steels. The increment of contamination on pure iron in point analysis is proportional to the number of iterations of beam irradiation, but not to the accumulated irradiation time. A combination of a longer dwell time and single measurement with a liquid nitrogen (LN2) trap as an anti-contamination device (ACD) is sufficient for a quantitative point analysis. However, in line and map analyses, contamination increases with irradiation time in addition to the number of iterations, even though the LN2 trap and a plasma cleaner are used as ACDs. Thus, a shorter dwell time and single measurement are preferred for line and map analyses, although it is difficult to eliminate the influence of contamination. While ring-like contamination around the irradiation point grows during electron-beam irradiation, contamination at the irradiation point increases during blanking time after irradiation. This can explain the increment of contamination in iterative point analysis as well as in line and map analyses. Among the ACDs, which are tested in this study, specimen heating at 373 K has a significant contamination inhibition effect. This technique makes it possible to obtain line and map analysis data with minimum influence of contamination. The above-mentioned FE-EPMA data are presented and discussed in terms of the contamination-formation mechanisms and the preferable experimental conditions for the quantification of trace carbon in steels. [ABSTRACT FROM AUTHOR]

A new method is proposed for the quantification of grain boundary segregation using Wavelength Dispersive Spectroscopy (WDS) in a Scanning Electron Microscope (SEM). Analyses are undertaken on a simple metallographically polished section of material. The method is demonstrated for the model system of sulphur segregation to nickel grain boundaries. Quantification was carried out from sulphur concentration profiles acquired across 11 grain boundaries of a nickel specimen containing 5.4 wt ppm of sulphur in the bulk and equilibrated at 550 °C. The average sulphur grain boundary concentration determined is µ =35.2 ng cm −2 =6.6×10 14 atoms cm −2 ≈0.5 monolayer, which is in good agreement with a previous quantification obtained from SIMS (Secondary Ion Mass Spectrometry) on the same material. However this is lower by a factor of two than the quantification obtained using “surface” techniques on fractured specimens of the same material. With the conditions of analysis used in this study, the limit of detection of the method developed is found to be better than 10% of a sulphur monolayer. [ABSTRACT FROM AUTHOR]

Based on thermodynamic calculations and a concept of miscibility gap, a new type of double-layer gradient WC–Co–Ti(C,N)–ZrC cemented carbides is prepared through liquid-phase sintering under vacuum at 1465 °C for 1 h. The core of the prepared cemented carbides consists of WC, (Co) binder phase and miscibility gap (Ti-rich and Zr-rich cubic phases), in addition to the surface layer (WC and Co-rich binder phase) and second layer (WC, binder phase and Ti-rich cubic phase). The prerequisite and mechanism for the formation of double layers have been clarified by means of microstructure characterization and thermodynamic calculations. [ABSTRACT FROM AUTHOR]

A diffusion couple between directionally solidified nickel and the single crystal Ni-base superalloy CMSX-10 was produced by hot pressing in vacuum. The diffusion couples were heat treated at temperatures between 1050 and 1250 °C. The exposed samples were characterized by SEM/EBSD/EPMA. The interdiffusion results in dissolution of the γ′-NiAl in the superalloy and in growth of nickel grains towards CMSX-10. Rapid diffusion of aluminum from the superalloy into pure nickel leads to a significant formation of pores in the superalloy. The interdiffusion processes were modelled using the finite-element simulation software DICTRA with the databases TCNi5 and MobNi2, tailored specially for Ni-base superalloys. The effect of alloying elements on the interdiffusion profiles is discussed in terms of alloy thermodynamics. The calculated element concentration profiles are in good agreement with the EPMA measurements. The interdiffusion modeling correctly predicts the shapes of the concentration profiles, e.g. kinks on the Al and Ti profiles in the vicinity of the original interface in the joint. The calculation predicts with reasonable accuracy the extent and the location of the Kirkendall porosity. [ABSTRACT FROM AUTHOR]

Phase equilibria in the quaternary Ni-Re-Nb-Cr system at 1375 K have been determined by using the graph method combined with equilibrated alloys that were characterized with electron probe microanalysis and x-ray diffraction techniques. Three 4-phase equilibria, α + β + λ + σ, α + β + λ + χ, and α + γ + σ + Re, and three nonprojected 3-phase equilibria, α + λ + χ, α + λ + σ and α + σ + χ, have been experimentally established. In addition, the graph method suggested the existence of the following four other 4-phase equilibria in this system at 1375 K, α + β + γ + σ, α + β + λ + μ, α + λ + σ + χ, and α + σ + χ + Re. [ABSTRACT FROM AUTHOR]

The Al-rich part of the Fe-Al phase diagram between 50 and 80 at.% Al including the complex intermetallic phases FeAl (ε), FeAl, FeAl, and FeAl was re-investigated in detail. A series of 19 alloys was produced and heat-treated at temperatures in the range from 600 to 1100 °C for up to 5000 h. The obtained data were further complemented by results from a number of diffusion couples, which helped to determine the homogeneity ranges of the phases FeAl, FeAl, and FeAl. All microstructures were inspected by scanning electron microscopy (SEM), and chemical compositions of the equilibrium phases as well as of the alloys were obtained by electron probe microanalysis (EPMA). Crystal structures and the variation of the lattice parameters were studied by x-ray diffraction (XRD) and differential thermal analysis (DTA) was applied to measure all types of transition temperatures. From these results, a revised version of the Al-rich part of the phase diagram was constructed. [ABSTRACT FROM AUTHOR]

Al and Zn are two of the most common alloying elements in commercial Mg alloys, which can improve the physical properties through solid solution strengthening and precipitation hardening. Diffusion plays a key role in the kinetics of these and other microstructural design relevant to Mg-alloy development. However, there is a lack of multicomponent diffusion data available for Mg alloys. Through solid-to-solid diffusion couples, diffusional interactions of Al and Zn in ternary Mg solid-solution at 400° and 450 °C were examined by an extension of the Boltzmann-Matano analysis based on Onsager's formalism. Concentration profiles of Mg-Al-Zn ternary alloys were determined by electron probe microanalysis, and analyzed to determine the ternary interdiffusion coefficients as a function of composition. The magnitude of $$\tilde{D}_{ZnZn}^{Mg}$$ ternary interdiffusion coefficients was greater than that of $$\tilde{D}_{AlAl}^{Mg} ,$$ the magnitude of $$\tilde{D}_{ZnZn}^{Al}$$ ternary interdiffusion coefficients was greater than that of $$\tilde{D}_{MgMg}^{Al}$$ , and the magnitude of $$\tilde{D}_{MgMg}^{Zn}$$ was greater than that of $$\tilde{D}_{AlAl}^{Zn}$$ . Appreciable diffusional interactions among Mg, Al, and Zn were observed by variations in sign and magnitude of cross interdiffusion coefficients. In particular, Zn was found to significantly influence the interdiffusion of Mg and Al significantly: the $$\tilde{D}_{MgZn}^{Al}$$ and $$\tilde{D}_{AlZn}^{Mg}$$ ternary cross interdiffusion coefficients were both negative, and large in magnitude, in comparison to $$\tilde{D}_{MgMg}^{Al}$$ and $$\tilde{D}_{AlAl}^{Mg}$$ , respectively. Al and Mg were observed influence the interdiffusion of Mg and Al, respectively, with positive $$\tilde{D}_{MgAl}^{Zn}$$ and $$\tilde{D}_{AlMg}^{Zn}$$ interdiffusion coefficients, but their influence on the Zn interdiffusion was negligible. [ABSTRACT FROM AUTHOR]

Liquid metal embrittlement induced cracking of zinc-coated twining induced plasticity steels was investigated during their resistance spot welding. Crack resistance of steel was investigated in relation to liquid metal embrittlement phenomenon. It was found that there are supercritical area and critical nugget diameter for cracking the welds. This suggests that crack-free welds are obtained only if the maximum nugget diameter being formed at expulsion current maintains below the critical nugget diameter of liquid metal embrittlement. Moreover, different Zn-coated (galvanized, galvannealed and electrogalvanized) twining induced plasticity steels are embrittled by liquid zinc but their cracking resistances are depended on chemical composition and process conditions of coating materials. [ABSTRACT FROM AUTHOR]

Corophium volutator (Pallas) has been recommended by the paris Commission as one of the standard species for testing chemical used in offshore oil and gas exploration/production. In the present study, gut contents of Corophium volutator have been analysed by electron probe microanalysis (EPMA) for BaSO4 and other heavy metal impurities after exposure tto spiked sediments following a standard ASTM sediment bioassay protocol. Results show that depuration of Corophium gut for 48 h in clean filtered seawater after exposure to sediments containing barites, prior to whole body metal analysis, is required to reflect the true metal burdens

• This is the first study of REEs fate by chemical extraction and microspectrometry. • The potential mobilization of REEs was mainly controlled by pedogenic Fe oxides. • The ratio of LREEs to HREEs varied among soils from different parent rocks. • HREEs were more enriched in soil Fe nodule relative to LREEs. • Pedogenic Fe oxides associated stronger with HREEs than with LREEs. Rare earth elements (REEs) from parent materials are easily trapped by secondary minerals in highly weathered soils that contain high pedogenic iron (Fe) oxide levels. However, few studies have investigated REEs fractionation by Fe oxides during pedogenesis. Therefore, this study examined REEs partitioned in the pedogenic Fe oxides of four pedons developed from schist, andesite, shale, and mafic rocks in Eastern Taiwan; this was achieved by combining the dithionite-citrate-bicarbonate (DCB) extraction for bulk soil samples and microspectroscopic approaches for thin sections. The DCB extraction was applied to pedogenic Fe oxides (Fe d). Furthermore, REE concentrations of the Fe extraction were measured to assess the potential mobility of REEs through the dissolution of pedogenic Fe oxides. The spatial distribution of REEs in Fe nodules and surrounding soil matrix was achieved by using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and electron probe microanalysis (EPMA). The results revealed that total REE content varied with soil depth and among pedons. Total REEs were fractionated during pedogenesis; thus, the ratio of light REEs (LREEs) to heavy REEs (HREEs) varied substantially among all pedons. However, the DCB-extractable REE contents significantly (p < 0.05) increased when the Fe d contents increased, indicating the high affinity of pedogenic Fe oxides for REEs. Moreover, the pedogenic Fe oxides exhibited an association preference for HREEs over LREEs even though the DCB-extractable concentrations of LREEs were higher than those of HREEs in the soils. Additionally, the association of REEs with Fe oxides led to HREEs condensation in the Fe nodules identified through LA-ICP-MS and EPMA. Our results elucidated pedogenic Fe oxides as the major carrier of REEs while clarifying the preferential trapping of HREEs by pedogenic Fe oxides. [ABSTRACT FROM AUTHOR]

Diffusion coefficients of the fcc Co–Al–W alloys were extracted from extensive diffusion couple experiments performed at 1173–1573 K, which were afterwards assessed to develop their diffusion mobility in the context of phenomenological treatment. We demonstrate that the mobility enables the prediction of diffusion picture of technologically important Co–Al–W alloys. [ABSTRACT FROM AUTHOR]

The depositional environment of the Upper Permian quartzose sandstone (Kuishan sandstone in Shihezi Formation of Upper Permian) in the North China epicontinental basin is controversial. In order to test the previous hypotheses, we analyzed sedimentological characteristics of the Kuishan sandstones in outcrops and boreholes, and carried out trace element geochemical analysis by electron probe microanalyzer. Three lithofacies were recognized, including normal-graded conglomerate (Cng), trough and planar cross-bedded coarse sandstone (CStpc), and planar cross-bedded medium sandstone (MSpc). Normal-graded conglomerate (Cng) formed in the meandering river or deltaic distributary channels. Trough and planar cross-bedded coarse sandstone (CStpc) formed in meandering river or distributary channels of near-source deltaic plain. Planar cross-bedded medium sandstone (MSpc) formed in the siliciclastic beach with high- to moderate-energy conditions. By the petrology and trace elements analysis, three relatively large-scale transgressions were revealed. Each transgression was reflected by the lower content of Ba and ratios of Fe/Mn, and the high content of B and ratios of B/Ga. The ratios of Ni/Co of all samples are all lower than 2, suggesting oxygen-enriched shallower water environment during deposition of the Kuishan sandstones. [ABSTRACT FROM AUTHOR]