EPMA Analysis Research Articles

High temperature oxidation resistance of TNM alloy coated with/without 8YSZ/NiCoCrAlY thermal barrier coatings

The oxidation resistance of the TNM alloy (Ti-44Al-4Nb-1.5Mo (B, Y) (at. %)) coated with/without 8YSZ/NiCoCrAlY thermal barrier coating (TBC) was conducted through cyclic oxidation at 950 ℃. The formation mechanism of oxide scale, interface interdiffusion mechanism, and evolution law of thermal growth oxide (TGO) were systematically investigated. Results show that the weight gains of the TNM alloy coated with/without TBC are 2.45 mg/cm2 and 6.98 mg/cm2, respectively. The Ti-Al-N layer and the (Nb, Mo)-rich layer near the surface play a role in blocking the internal diffusion of air and the external diffusion of metal ions. After a comprehensive analysis of EPMA and SEM results, it is concluded that the diffusion rate of elements in NiCoCrAlY is Ni > Co > Cr. At the same time, the relationship between the interface diffusion layer thickness and oxidation time is built based on Fick’s first law. In addition, as the oxidation time increases, TGO evolves from a dense Al2O3 layer to CS (chromia, spinel oxide) layer, and CSN (chromia, spinel, and nickel oxide) cluster oxides. The mixed oxides induce crack nucleation and growth, thereby reducing TBC lifetime.

Peracetic acid as a novel blowing agent in the direct foaming of alkali-activated materials

In this study, peracetic acid (PAA) was investigated as a novel blowing agent for the preparation of porous alkali-activated materials from metakaolin or blast furnace slag by the direct foaming method. PAA is an organic peroxide with lower stability of the OO bond in comparison to H2O2. It also introduces acetate anions to the system, which can chelate cations to potentially increase the extent of precursor dissolution and decrease the surface tension of the gas-liquid interfaces prompting open porosity formation. PAA was compared with H2O2 to prepare porous alkali-activated materials by characterizing setting time, compressive strength, reaction kinetics (by isothermal calorimetry), porosity (by mercury intrusion porosimetry and helium gas pycnometry), and chemical composition (by electron probe microanalyzer, EPMA). The most significant finding was that the use of PAA caused 92%–94% and 72%–80% lower volume increase compared to H2O2 upon curing for metakaolin and blast furnace slag-based foams, respectively. The enhanced dissolution of the precursors when using PAA were observed from the EPMA analysis, which promoted higher compressive strength for PAA-based foams (451–537% compared to H2O2-based foams). There was also an indication that the use of PAA promoted the open porosity formation. As a practical implication, PAA could be well suited for applications in which the volume increase during the foam setting must be minimized.

Varying processes, similar results: How composition influences fragmentation and subsequent feeding of large pyroclastic density currents

Unlike their silicic counterparts, mafic eruptions are known for being on the low-end of the explosivity spectrum with eruption styles commonly ranging from effusive to Hawaiian fire fountaining. However, there are increasing discoveries of large mafic Plinian eruptions, sometimes generating ignimbrites, suggesting that this phenomenon might not be so uncommon. So, what processes lead a mafic magma to fragment violently enough to generate extensive ignimbrites?We sampled pumices from ignimbrites and PDCs with a compositional range from basaltic-andesite (Curacautín ignimbrite, Volcàn Llaima, Chile), andesite (Marapi, Indonesia) to trachyte (Gunungkawi ignimbrite, Batur, Indonesia). We use SEM imagery and X-ray Microtomography on pyroclasts from these deposits to characterize phenocryst, microlite and vesicle textures. From vesicle number densities we estimate fragmentation decompression rates in the range of 0.4–1.6 MPa/s for the three deposits. With a combination of EPMA and SIMS analyses we characterise pre-eruptive storage conditions. Based on the bulk and groundmass compositions, the storage temperature (1,050–1,100°C), pressure (50–100 MPa) and phenocryst content (1.0–2.5 vol%), we conclude that the basaltic-andesitic Curacautín magma was at sub-liquidus conditions, which allowed fast and widespread disequilibrium matrix crystallization (0–80 vol%) during ascent to the surface. Combined with the important decompression rate, this intense crystallization led to a magma bulk viscosity jump from 103 up to >107 Pa s and allowed it to fragment brittlely. Conversely, for the Marapi PDC and Gunungkawi ignimbrite, similar decompression rates coupled with larger initial bulk viscosities of 105–106 Pa s were sufficient to fragment the magma brittlely. The fragmentation processes for these latter two deposits were slightly different however, with the Marapi PDC fragmentation being mostly driven by vesicle overpressure, while a combination of bubble overpressure and intense strain-rate were the cause of fragmentation for the Gunungkawi ignimbrite. We conclude that mafic ignimbrites can form due to a combination of peculiar storage conditions that lead to strongly non-linear feedback processes in the conduit, particularly intense microlite crystallization on very short timescales coupled with intense decompression rates. Conversely, the high viscosity determined by pre-eruptive storage conditions, including temperature and volatile-content, are key in controlling the formation of more evolved magmas PDCs'.

Interfacial Behaviour in Ferroalloys: The Influence of FeMn Slag Composition

The present study investigated the interfacial interaction between FeMn alloy and slags of different compositions and basicity from 0.4 to 1.2 in a sessile drop furnace. Interfacial tension between the FeMn alloy and the slags was measured, and the results were analyzed to assess the sensitivity of the applied methodology. The measurement of the interfacial tension was based on combining the results from experiments, multiphase flow simulations in OpenFOAM, equilibrium calculations in FactSage, and calculation of slag density and surface tension based on numerical models. The results demonstrate that the interfacial tension between the FeMn alloy and slag increases with the slag basicity. It was found that the addition of Al_{2}O_{3} to the slag with basicity of 0.8 and 1.2 increases the interfacial tension, while increasing MnO content from 30.0 to 45.0 wt pct does not have any statistically significant influence on the interfacial tension. EPMA analysis of slag and FeMn phases showed that slags at lower basicities and the FeMn alloy form a metal–slag emulsion due to the destabilization of the interface induced by chemical reactions, partial reduction of SiO_{2} in the slag and the mass transfer of Si across the metal–slag interface.

Petrogenesis of the Early Cretaceous Zhouguan Granodiorite in Jiaodong Peninsula: Evidence from Mineralogy, Geochemistry, Geochronology, and Sr-Nd Isotopes

The Jiaodong Peninsula is the most important gold mineralization area in China, and the formation of gold deposits is closely related to granitoids. The isotopic ages of the Early Cretaceous granodiorites in the northwestern Jiaodong Peninsula are concentrated in the range of 111~123 Ma, and are coeval with the formation of the gold deposits in the area. However, the studies on the geotectonic settings of the granodiorites, especially their petrogenesis and relationship with gold deposits in the northwestern Jiaodong Peninsula, are scarce. Based on field and petrographic observations, geochemistry, EPMA analysis, zircon U-Pb chronology, and Sr-Nd isotopes of the Early Cretaceous Zhouguan granodiorite in the Jiaodong area, the formation age of Zhouguan granodiorite is determined as 115 Ma ± 0.77 Ma; the analysis of EPMA shows that biotite is mainly composed of Fe-biotite and Mg-biotite, with its MgO content ranging from 9.797% to 11.635%. The crystallization temperature of biotite is in the range of 500 °C~625 °C and the emplacement depth of the rock mass is 3.98~8.71 km. The amphibole in the mass mainly includes magnesiohornblende, pargasite, and magnesiosadanagaite; among them, the former two are of crustal origin, while magnesiosadanagaite is of mantle origin. The crystallization pressure and depth of the former two are in the range of 0.75~3.02 kbar and 2.81~11.4 km, respectively, while the crystallization pressure and depth for the latter is 4.64 kbar and 17.53 km, respectively. The (87Sr/86Sr) values range from 0.710424 to 0.711074 and the (143Nd/144Nd) values range from 0.511530 to 0.511808. The parental magma of the Zhouguan granodiorite is highly oxidized with high-water content that is favorable for Au enrichment. Combined with the Nb-Y and Yb-Ta diagrams, a model describing the formation of Zhouguan granodiorite is proposed.

Phase equilibria of SiO2–Ce2O3–CaO-25 wt %Al2O3 system at 1673 K–1773 K

The utilization of rare earth resources, especially secondary resources (e.g., RE-oxide system slag), has been limited by the lack of thermodynamic information. In order to supplement and improve the thermodynamic data related to rare earth, the equilibrium experiments of SiO2–Ce2O3–CaO-25 wt %Al2O3 system phase diagram was carried out at 1673 K and 1773 K by the high-temperature isothermal equilibration/quenching technique in current paper. The composition of seven phase regions were determined by FE-SEM, XRD, EPMA and XRF analysis on the samples obtained by high temperature equilibrium technology at 1673 K and 1773 K, including the primary crystal regions of three compounds (C2AS, 2CaO·SiO2, CaO·2Ce2O3·3SiO2) and three three-phase coexistence regions (L + C2AS + 2CaO·SiO2, L + C2AS + CaO·2Ce2O3·3SiO2, L + CaO·2Ce2O3·3SiO2+CeAl11O18) and a liquid region. The phase relations and isotherms of SiO2–Ce2O3–CaO-25 wt %Al2O3 system obtained in current work are beneficial to the recycling of rare earth resources containing cerium.

Vanadium and Cobalt Occurrence in the Fe-Ti-V Oxide Deposits Related to Mesoproterozoic AMCG Complex in NE Poland

On the basis of geochemical whole-rock and mineralogical point analyses, the concentrations of V and Co were determined in magnetite-ilmenite oxide ores, associated with sulphides, at the Krzemianka and Udryn deposits in the Mesoproterozoic Suwałki Anorthosite Massif (SAM) in NE Poland. EPMA analyses showed that the main carrier of vanadium was magnetite (mean = 0.42 wt%) and, to a lesser extent, ilmenite (mean = 0.14 wt%) and minor Al-spinels (mean = 0.04 wt%). In turn, cobalt was found mainly in the form of isomorphic substitutions in magmatic sulphides such as pentlandite (mean = 4.41 wt% Co), pyrrhotite (mean = 0.16 wt%), and chalcopyrite (mean = 0.11 wt%). Moreover, Co-enrichments were also recognized in the secondary sulphides, such as pyrite and bravoite, replacing pyrrhotite (means = 1.6 and 2.7 wt% Co, respectively), and in the form of different thiospinels ((Fe, Ni) (Co, Ni)2S4), mainly siegenite (mean = 22.0 wt% Co), replacing pyrrhotite and pentlandite. Vanadium cations were substituted in Fe, Ti oxide minerals in place of Fe+3 cations, and in the case of cobalt, Fe+2 cations were substituted in sulphides and thiospinels. Vanadium and cobalt showed high Person’s correlation coefficients (r = 0.70), indicating their close spatial coexistence and a common source, which was parental anorthosite-norite magma of the SAM suites. The common magma genesis of magnetite-ilmenite and sulphide mineralization was also confirmed by the very similar shapes of the curves of REE content in the oxide-sulphide ores in relation to chondrite, in which negative Eu anomalies and positive Sm anomalies are clearly visible. Although the average contents of vanadium and cobalt were low (arithmetic means = 960 ppm, and 122 ppm, respectively), the resources of these metals were estimated to be large due to the enormous reserves of magnetite-ilmenite ores hosted by the SAM. However, the Fe-Ti-V ores associated with Fe, Ni, Co, and Cu sulphides were considered to be sub-economic because of their depth of occurrence (mainly 1.0 km below the surface level); their metal contents, which were usually too low; and additionally the fact that the location is in a highly environmentally protected landscape and lake area.

EVALUATION OF THERMAL METAMORPHISM TEMPERATURE OF EQUILIBRATED ORDINARY CHONDRITES

The article provides an evaluation of thermal metamorphism temperatures on chondrite parent bodies using an olivine-Сr spinel geothermometer. To calculate temperatures, the results of EPMA analysis of the major and trace elements in olivine and Cr spinel of Kargapole, Orlovka, Saratov, Elenovka, Buschhof, Bjurböle and Knyahinya meteorites are used. The obtained temperatures are consistent with the onion-shell model of the planetesimal structure, in which the most metamorphosed chondrites are closer to the heating source (Buschhof, L6-734 °C), meteorites of the 5th petrologic type (p.t.) occupied an intermediate position (Orlovka, H5 – 687 °С; Elenovka, L5 – 691 °С; Knyaginya, LL5 – 700 °C), and the chondrites of the 4th p.t. were closer to the surface (Kargapole, H4 – 691 °C; Saratov, L4 – 670 °С; Bjurböle, LL4 – 682 °C). The Kargapole and Saratov meteorites are characterized by evaluation of Mg and Fe equilibrium temperatures that disagree with the onion-shell model, which can be explained by the individual history of the meteorite (for example, impact metamorphism, slow and prolonged heating).

The origin and localization of “vermiculite” along the intra‐terrane shear zones in the Bundelkhand Craton, India: Mechanism and implication

Vermiculite, a clay mineral of economic importance, is reported for the first time from the Bundelkhand Craton. The locales of the vermiculite occurrence are mapped within the Bundelkhand granitoids at several places. The identification of the fracture system and the zones of strain localization within Bundelkhand granitoids are critical for targeting the occurrences of vermiculite. A range of studies including meso‐, micro‐, and sub‐microscopic analyses were used to delineate the characteristic features of vermiculite along the brittle/ductile shear zones in the Bundelkhand Craton. SEM‐based EDS, EPMA, and XRD analyses confirm the ubiquitous dominance of vermiculite as fracture infills and/or channel infill materials along the zones of nucleation of ductile shear zones. It is postulated here that the occurrence of vermiculite is a result of supergene alteration of biotite present in the vein material. The parent material of the fracture infills from which the veins crystallized is genetically derived from the host rock (Bundelkhand granitoid), which later healed the fractures and prompted the nucleation of ductile shear zones in the Bundelkhand Craton.

Origin of the Shanggong gold deposit, the southern margin of the North China Craton: Constraints from Rb-Sr ages of sericite, and trace elements and sulfur isotope of pyrite

The Shanggong Au deposit is a world-class Au deposit in the southern margin of the North China Craton. Pyrite, as the primary Au carrier in this deposit, is an ideal mineral for dissecting the complex ore-forming process and origin of this deposit. Four types of pyrite were identified by EPMA, SEM, LA-ICP-MS, and NanoSIMS analyses: the coarse-grained cubic, disseminated pyrite (Py1) in the early ore stage (S1) and three types of the fine-grained pentagonal dodecahedron, disseminated pyrite (Py2-1, Py2-2, and Py2-3) with zoning textures in the main ore stage (S2). Py1 is relatively depleted in most metals but enriched in Co and Bi compared with other types of pyrite in S2. On the other hand, both Py2-1 and Py2-3 contain relatively high contents of As, Au, and other metals, whereas Py2-2 contains highest Au, As, Ag, Cu, Sb, Te, Tl, and Pb. Oscillatory zoning in Py2-1 resulted from repeated local fluid phase separation at the near-surface of pyrite crystal due to sharp fluid pressure fluctuation. The Au and As-rich Py2-2 was probably formed under both extrinsic fluctuations in fluid pressure and composition and intrinsic local crystal-fluid interface kinetic effects (e.g., diffusion-limited self-organization, surface electrochemistry-driven adsorption). Crystallization of Py2-1 and Py2-2 has exhausted the metals in the residual fluids, wherein the trace element-poor Py2-3 crystallized and locally replaced Py2-2 through a dissolution-reprecipitation process. Our new data and previous results suggest the ore-forming fluids were likely initial produced by degassing of the concealed pluton, and the metals were sourced from both the crust (e.g., the Taihua complex and Xiong’er Group) and the mantle. The negative δ34S values for pyrite in the S2 stage might result from both the isotopic fractionation between sulfide and sulfate minerals via oxidation of the ore-forming fluid and the input of biogenic sulfur.

Immobilization of fluorides from spent carbon cathode in a copper smelting slag

The fluorides from spent carbon cathodes could be effectively solidified in a molten copper smelting slag (FeO-Fe3O4-SiO2- CaO-Al2O3) in forms of CaF2 and Ca4Si2F2O7. The results of thermodynamic analysis, chemical analysis, and XRD and EPMA analyses showed that the F solidification efficiency increased with the CaO amount and decreased with the addition of Al2O3 and SiO2. In addition, it was noteworthy that the F solidification efficiency decreased with an excessive CaO amount, which could be ascribed to the consumption of SiO2 through forming CaSiO3 and Ca3Si2O7. It restricted the solidification of the fluoride into Ca4Si2F2O7. Under the conditions of melting temperature of 1300?C, residence time of 60 min, and N2 flow rate of 40 ml/min, the optimum CaO and NaF amounts were found to be 20 wt.% and 6 wt.%, respectively, in which the F solidification efficiency in the copper smelting slag of FeO-Fe3O4-SiO2-CaO-Al2O3 obtained 98.35%.

Effects of Carbon and Phosphorus on Microstructure and Mechanical Properties of Friction Stir Welded Weathering Steels

Weathering steels with the increased concentration of carbon (C) and phosphorus (P) that tend to be difficult to join without defects by fusion welding were fabricated by friction stir welding (FSW), and the effects of C and P contents on the microstructure and mechanical properties of FSWed joints were investigated. P segregation formed during solidification was present in the base material (BM) of the steels. In the stir zone (SZ) of FSWed joints, P segregation was reduced under the condition of higher welding temperature (above A3). In the tensile test, both the addition of C and P increased tensile strength. On the other hand, the increase in C content impaired the uniform elongation, while the increase in P content did not deteriorate it. It is because the work hardening rate was improved by the P addition presumably due to the suppression of cross slip of dislocations. In the Charpy impact test, the increase in C and P contents shifted the DBTT to the higher temperatures and simultaneously decreased the upper shelf energy. EPMA analysis performed on the cross-section of the ductile fracture surface of BM of 0.3 wt%P steel revealed that voids were formed at the boundary between P segregated area and the non-segregated area. Therefore, P segregation was inferred to be the main factor determining the upper shelf energy. Since the P segregation of the joint FSWed above A3 was improved, the upper shelf energy of the SZ was the highest among BM and SZ FSWed below A1.

Analysis and application of yttrium element in garnet by electron micro-probe analyzer: A case study of garnet-mica schist from Foziling Group

石榴石是最重要的造岩矿物之一，通常能够保留早期的矿物结构和物质并记录较为晚期的变形和变质反应。石榴石钇（Y）元素环带特征丰富、复杂，不同的环带特征通常暗示不同的形成环境或经历了不同的变质事件，是变质演化历史研究的重要媒介之一。以往的研究中，多以LA-ICP-MS作为石榴石Y元素的主要分析手段，EPMA主要用于主量元素的分析。但是，LA-ICP-MS的束斑尺寸（44μm）和基底效应较EPMA （0~5μm）大，当石榴石颗粒小、包体和裂隙发育或成分环带以微区尺寸内存在较大变化时，大束斑更容易覆盖某些特殊信息。通过对石榴石Y元素测试参数的调试和标样验证，最终确定峰位测试时长和背景测试时长分别为140s和70s，并进行了PHA谱峰干扰剥离，降低检测限至54×10^-6。本文将通过对比佛子岭石榴云母片岩（LD025）4颗石榴石的EPMA主、微量原位分析（Ca、Mg、Mn、Fe、Y、Al、Si、Cr、Ti、Na）和LA-ICP-MS石榴石Y元素分析结果，论证EPMA分析Y元素的可行性。石榴石X-ray Mapping和主量成分剖面揭示该4颗石榴石均为生长环带，Mn呈钟形分带，Y与XSps呈强烈正相关性，与XGrs、XAlm、XPrp相关性不清晰。EPMA和LA-ICP-MS分析结果显示Y含量曲线在核部和幔部具有良好的一致性，Grt1~Grt3中Y均表现出自核部（500×10^-6~1200×10^-6）向幔部（200×10^-6~500×10^-6）逐渐降低，极边部Y含量低（20×10^-6~200×10^-6）且变化复杂；Grt4中Y含量差异相对较小（180×10^-6~450×10^-6），仅在边部出现不同程度的升降。因EPMA对于Y元素含量较低（<200×10^-6）时灵敏度不够或者LA-ICP-MS束斑尺寸大容易掩盖边部窄带成分真实变化等原因，二者在边部Y元素差异较大。分别对EPMA和LA-ICP-MS的分析结果应用Grt-Xtm温度计和Grt单矿物压力计获得的变质PT结果显示Grt1~Grt3（核-幔-边）和Grt4（核-边）均记录较为完整、统一的温压演化过程。M1→M2→M3的变质温压变化分别为T=530~544℃、P=0.78~0.82GPa→T=577~616℃、P=0.89~0.98GPa→T=631~661℃、P=1.01~1.07GPa，表现为顺时针演化型式，M1至M3反映的是一个暖俯冲过程。根据温度评价结果，Grt1~Grt3（1.2~1.4mm，自形程度高）形成时间应早于Grt4（0.8mm，自形程度低）。由此可知，大颗粒的石榴石Y元素含量及变化特征通常更容易揭示相对完整的变质演化历史。本次研究为变泥质岩演化历史、变质温压评价等研究提供了不同视角和思路，结合EPMA主量（矿物成分、X-ray mapping、BSE分析）和微量元素（Y等）分析能够更加精准、全面地解读地质信息。;Garnet is one of the most rock-forming mineral in the earth, it can record not only the former mineral's composition and structure, but also later deformation history and metamorphic reactions of rocks. In previous studies, LA-ICP-MS was mostly used as the main analysis method of yttrium (Y) in garnet, and EPMA was mainly used for analysis of major elements. However, the beam spot size (44μm) and basement effect of LA-ICP-MS are larger than those of EPMA (0~5μm). When garnet particles are small, inclusions and fractures are developed, or there are large changes in the micro area size of the composition ring, the large beam spot is easier to cover some special information. Through the debugging of garnet Y analysis parameters and standard sample verification, it is finally determined that the peak position and background counting time are 140s and 70s respectively, and the PHA spectrum peak interference stripping is carried out to reduce the detection limit to 54×10^-6. The paper will demonstrate the feasibility of EPMA analysis of Y by comparing the results of EPMA main and micro in-situ analysis (Ca, Mg, Mn, Fe, Y, Al, Si, Cr, Ti, Na) and LA-ICP-MS garnet Y content analysis. Garnet X-ray mapping and component profile reveal that the four garnets are characterize by growth ring, and the bell shaped zoning of Mn is typical. Among them, Y has a strong positive correlation with XSps, and the correlation with XGrs, XAlm and XPrp is not clear. The results of EPMA and LA-ICP-MS analysis show that the Y content curves are in good agreement both core and rim. Yttrium in Grt1~Grt3 is characterized by a gradual decrease from the core (500×10^-6~1200×10^-6) to the mantle (200×10^-6~500×10^-6), the extreme rim with low Y (20×10^-6~200×10^-6) and the change is complex. The difference of Y content in Grt4 is relatively small (180×10^-6~450×10^-6), and there are only different degrees of rise and fall at the outer edge. Due to the insufficient sensitively of EPMA to low Y content (<200×10^-6) or the large beam spot size of LA-ICP-MS, which is easy to cover up the real change of narrow rim Y composition, the two have great differences Y contents in the rim section. Based on the analysis results of EPMA and LA-ICP-MS, the metamorphic PT conditions obtained by Grt-Xtm thermometer and Grt single mineral geobarometer show that Grt1~Grt3 (core-mantle-rim) and Grt4 (core-rim) record a relatively complete and unified metamorphic PT evolution process. The metamorphic PT changes of M1→M2→M3 are T=530~544℃and P=0.78~0.82GPa→T=577~616℃ and P=0.89~0.98GPa→T=631~661℃ and P=1.01~1.07GPa respectively, showing a clockwise evolution pattern. M1 to M3 reflect a warm subduction process. According to the PT results, the formation time of Grt1~Grt3 (1.2~1.4mm, high automorphism) should be earlier than Grt4 (0.8mm, lower automorphism). Therefore, the content and variations characteristics of Y in large grain garnet are usually easier to reveal the relatively complete metamorphic evolution process. This study provides different perspectives and ideas for the study of metamorphic argillaceous rock evolution history and metamorphic temperature. Combined with EPMA major element (composition, X-ray mapping and BSE analysis) and trace element (Y, etc.) analysis, the geological information can be interpreted more accurately and comprehensively.

Comparative Study on the Origin and Characteristics of Chinese (Manas) and Russian (East Sayan) Green Nephrites

Green nephrites are widely pursued for their mild texture and vivid color. In recent years, many Russian green nephrites appeared in China (the world’s largest nephrite market) and competed with the Chinese Manas green nephrites, which are traditionally highly valued. In this study, we compared the appearance, mineralogy and geochemical features (with EPMA and LA-ICP-MS) of Chinese (Manas) and Russian (East Sayan) green nephrites to objectively characterize and distinguish between these two nephrites. Chinese (Manas) and Russian (East Sayan) green nephrites are mined from serpentinized ultramafic units in the northern Tian Shan and East Sayan orogen, respectively. In terms of appearance, the Manas green nephrites are slightly bluish or grayish, whilst their East Sayan counterparts are brighter (duck-egg cyan). The Manas nephrites commonly have a caramel color, crumple structure, characteristic white globules and sinuous veins, green stains and yellow–green veins, together with a local fibrous structure. The East Sayan green nephrites are more transparent, with a gentler fine texture, uniform color, many black spots and a few green spots. Some green nephrites from the Arahushun mine of East Sayan have an ice-like appearance. Microscopic petrography and EPMA analysis indicate that both the Manas and East Sayan green nephrites comprise mainly tremolite with minor actinolite. Minor minerals in the Manas samples include chromite, chlorite-group minerals, and uvarovite; whilst those in the East Sayan samples include actinolite, chromite, chlorite-group minerals, and bornite. Bornite is not found in any other sources of green nephrite, and thus is characteristic of Russian (East Sayan) green nephrites. LA-ICP-MS trace element data in their amphiboles and Single-Factor Analysis of Variance (ANOVA) results suggest that the differences in Cr, Zn, Y, Ba, and Sr contents and values of δEu, Eu/Sm, (La/Yb)N, (La/Sm)N, (Gd/Yb)N, ∑HREE, ∑LREE/∑HREE between the two nephrites are present, and can be used as their origin trace.

Structure of Alloys for (Sm,Zr)(Co,Cu,Fe)z Permanent Magnets: III. Matrix and Phases of the High-Coercivity State.

Observations of the surface domain structure (Kerr-effect), optical metallography, scanning electron microscopy (SEM-SE), and electron microprobe analysis (EPMA-SEM), measurements of major and minor magnetic hysteretic loops were used to study pseudo-single-crystal samples of (Sm,Zr)(Co,Cu,Fe)z alloys subjected to heat treatments to the high-coercivity state, which are used in fabricating sintered permanent magnets. Correlations between the chemical composition, hysteretic properties, structural components, domain structure, and phase state were determined for the concentration ranges that ensure wide variations of 4f-/4d-/3d-element ratio in the studied samples. The phase state formed by collinear and coherent phase components determines the high coercive force and ultimate magnetic hysteresis loops of the pseudo-single crystals. It was found that the 1:5 phase with the hexagonal structure (P6/mmm) is the matrix of the alloys for (Sm,Zr)(Co,Cu,Fe)z permanent magnets; the matrix undergoes phase transformations in the course of all heat treatments for the high-coercivity state. The heterogeneity observed with optical magnifications, namely, the observation of main structural components A and B, is due to the alternation, within the common matrix, of regions with modulated quasi-spherical precipitates and regions with hexagonal bipyramids (cellular phase) although, traditionally, many investigators consider the cellular phase as the matrix. It is shown that the relationship of volume fractions of structural components A and B that account for more than 0.9 volume fraction of the total, which is due to the integral chemical composition of the alloys, determines the main hysteretic performances of the samples. The Zr-rich phases, such as 5:19, 2:7, and 6:23, and a structural component with the variable stoichiometry (Sm(Co,Cu,Fe)3.5–5) that is almost free of Zr and contains up to 33 at% Cu, were found only within structural component A in quantities sufficient for EPMA analysis.

Chemical interaction between uranium dioxide, boron carbide and stainless steel at 1900 °C — Application to a severe accident scenario in sodium cooled fast reactors

For the understanding of severe accidents in sodium cooled fast reactors (SFR), it is necessary to understand two prototypic accident scenarios such as ULOF (Unprotected Loss of Flow Accident) and UTOP (Unprotected Transient OverPower). As the base knowledge, it is also important to understand high temperature chemical interaction among major core materials such as MOx fuel (MOx: mixed oxide of uranium and plutonium), steel cladding and B4C neutron absorber have to be investigated. This study aims at providing experimental data on phase formation and phase-stability at various temperature and pressure conditions. A first series of samples containing a mixture of B4C and steel were prepared to obtain a homogenous metallic solid. In a second step, these metallic samples were mixed and melted with small UO2 pieces by arc melting. Then these samples underwent a heat treatment at 1900 °C for 1 hour. EDS, EBSD and EPMA analyses were performed to identify the phases formed during the solidification. In addition, thermodynamic calculations were performed for the interpretation of the results, revealing that a carbo-reduction reaction occurs: UO2 + 2 C = 2 CO + U. A significant amount of uranium from the fuel is dissolved in the metallic liquid phase, leading to the formation of mixed borides (UM3B2, UMB4, UM4B, M=Fe,Cr,Ni). In comparison with the UO2/steel interaction, the present results show that the presence of B and C in the melt improves the wetting behaviour of the metallic liquid towards UO2.

Identification of Fe3+ content in Epidote from Varan, Urumieh-Dokhtar Magmatic Arc, Iran: using FTIR and Raman spectroscopy

This study is aimed to determine the Fe content in natural epidote from Varan area (Urumieh-Dokhtar Magmatic Arc, Iran) by using vibrational FTIR and Raman spectroscopy and EPMA analyses. Fe3+ concentration calculated from FTIR spectroscopic data is in the range of 0.96 to 1 apfu. The results are in complete agreement with EPMA data. The comparison between obtained Raman spectra of studied epidote grains and those from the RRUFF database suggest that epidote from Varan area is rich in Fe3+. High Fe3+ content might reflect moderate to high oxygen fugacity during the crystallization of epidote. This short paper demonstrates that the quantification of the Fe content in epidote via FTIR method is as good as EPMA, whereas the utilization of a low-cost Raman spectrometer helps in quickly distinguishing between Fe-rich and Fe-poor epidote, which even could be useful in the case of field studies.spectrometer helps in quickly distinguishing between Fe-rich and Fe-poor epidote, which even could be useful in the case of field studies.Key-words: Epidote, FTIR, Raman spectroscopy, Iron content, Urumieh-Dokhtar Magmatic Arc, Iran.

Extraction of copper from complex carbonaceous sulfide ore by direct high-pressure leaching

The increase of impurities and complexity of copper ores are among the recent challenges in the mining industry. Complex carbonaceous sulfide ores are extremely difficult to treat due to their mineralogical complexity and impurities of organic carbon and carbonates. This study focuses on the development of a hydrometallurgical process for efficient copper extraction from complex carbonaceous sulfide ore which contains chalcopyrite, carbonates (dolomite and calcite), and carbonaceous gangue minerals. Characterization of the ore sample and leach residues was conducted using XRD and EPMA analysis, while ICP-OES was used for the determination of total dissolved metals in solution. High-pressure leaching of complex carbonaceous sulfide ore in oxygenated sulfuric acid solution was performed and the influence of leaching parameters such as sulfuric acid concentration, temperature, total pressure, and pulp density was studied. The extraction of copper increased with increasing temperature, sulfuric acid concentration, and total pressure. On the other hand, an increase in pulp density resulted in a decline in copper extraction due to an increased slurry viscosity and resistance in the diffusive mass transfer of reactants. Selective dissolution of copper from iron can be achieved by controlling free acidity in the pregnant leach solution (PLS). Under these leaching conditions: 100 g/L, 1 M H2SO4, 160 °C, 1.0 MPa total pressure, the highest copper and iron extractions achieved were 97.55% and 95.37%, respectively. Precipitation of copper from the PLS by NaSH sulfidization was investigated and more than 99.9% of copper was recovered at a Cu: NaSH molar ratio of 1:1.8.

Blueschists and Blue Amphibole Schists-Gneisses Associated with the Nan River Mafic – Ultramafic Belt, North Thailand

The discovery of an areally limited outcrop of blueschists in Huai Sak, near Ban Huai Lao, SE Nan Province in the early 1980s has not been followed up until now. This is despite these blueschists being used in many regional tectonic compilations as unequivocal evidence for the presence of a former subduction zone along the trend of the Nan river. We report additional structural information and mineral analyses for the Huai Sak blueschists and the discovery nearby, in Huai Phi Rong, of structurally similar schists containing the Na-Ca amphibole barroisite. In addition, we report the discovery in Huai Phi Rong of float samples, believed to be derived from a thrust sheet of serpentinite matrix melange, consisting of coarse schists and gneisses that contain a variety of blue amphiboles associated with garnet. EPMA analysis confirms these blue amphiboles to be variously riebeckite, glaucophane, winchite and barroisite.

Hot corrosion-creep interaction in IN718 under simulated marine environment: Introducing strain-associated-time (SAT) plots for comprehensive understanding

Creep-rupture behaviour of IN718 with deposit of 87.5 wt.%Na2SO4+5 wt.%NaCl+7.5 wt.%NaVO3 (3SM) in the stress range of 550–850 MPa at 650 °C is investigated. 3SM shortens the creep-rupture time by ≈70–90 %. Comprehensive microstructural analysis suggests that oxygen-induced-dynamic- embrittlement, sulphidation followed by oxidation, and vanadic-hot corrosion operate during creep. Creep-hot corrosion interaction influence on rupture strain is explained by introducing strain-associated-time (SAT) and Δtε plots, for the first time. These plots accompanied by detailed microstructural examination demonstrate that deleterious influence of 3SM increases with decreasing stress. Further, SAT plots and EPMA analysis confirm that oxygen-induced-dynamic-embrittlement commences from ∼9% strain under 3SM at 550 MPa.