Energy Dispersive Microprobe Research Articles

Phase Relations of the Sm–Ni–Al Ternary System at 800 °C in the 30–100 at.% Al Region

The Sm–Ni–Al phase relationships at 800 °C have been investigated by using several well–focused experimental techniques such as X–Ray Powder Diffraction (XRPD), Light Optical Microscopy (LOM) and Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Microprobe Analysis (EPMA). The isothermal section of the Sm–Ni–Al system at 800 °C was constructed according to the present experimental results. More than 50 alloys have been synthesized and characterized in the 30–100 at.% Al region. At 800 °C, 9 intermetallic phases have been confirmed, characterized and their relationships have been established. In the Al-rich corner, the presence of two ternary invariant reactions have been postulated whilst along the 16.67 at.% Sm isopleth, the presence of two structurally related extended solid solutions have been observed. The determined phase equilibria at 800 °C are discussed and compared with the isothermal section at 500 °C already reported in literature.

Microstructure evaluation of dissimilar AA2024 and AA7050 aluminum joints made by corner stationary-shoulder friction stir welding

Fillet welds made by the corner stationary-shoulder friction stir welding process between AA7050-T7451 and AA2024-T4 sheets were characterized using different metallographic techniques and mechanical testing. Robotic welds of an aircraft’s skin-to-internal stiffeners were examined using Barker’s electrolytic and Keller’s etching techniques and correlated with electron backscattered diffraction results and energy-dispersive microprobe analysis. The composition and grain orientation maps and material flow lines demonstrated excellent weld quality in spite of the apparent inhomogeneities in the stir zone where mechanical mixing was complete. Welded joint efficiencies were in the 85–92% of the base metals and were acceptable in terms of resistance to crack initiation and propagation and corrosion resistance, even with softening of the heat-affected zones. It was concluded that several optical and electron microscopy techniques are needed to characterize these dissimilar aluminum welds fully and that post-weld mechanical and thermal treatments could even further improve their quality.

Automatic analysis of nonmetallic inclusions in steel using electron microscope with energy dispersive microprobe with

Clean steel non-metallic inclusions have a significant effect on the physic and mechanical as well as technological properties of the metal and consequently on the quality of the final product. There are many methods for detecting and evaluating nonmetallic inclusions. Traditional methods for assessing the contamination of metal with microinclusions are metallographic methods, which are divided into methods for comparing the contamination of the section with inclusions with reference scales and counting methods. The classification of inclusions by traditional methods on a polished section is based on morphological features: shape, color, aspect ratio, etc. In addition to traditional optical microscopy, an electron microscope is used for studies that are more detailed. Equipping an electron microscope with an attachment for energy-dispersive microanalysis allows classifying nonmetallic inclusions by chemical classes. As a result of the implementation of a set of organizational and technical measures, BMZ, the management company of BMK Holding, installed and put into operation research equipment in December 2020 – a scanning electron microscope with an energy-dispersive microanalyzer (SEM with EMF). Thanks to the software module that the microanalyzer is equipped with, the possibility of automatic analysis of non-metallic inclusions is implemented. The software settings include the search for non-metallic inclusions and their classification according to widely used international standards. The flexible configuration of the software allows you to create models for separating inclusions into different user classes.

Materials for High Temperature Liquid Lead Storage for Concentrated Solar Power (CSP) Air Tower Systems.

Today the technical limit for solar towers is represented by the temperature that can be reached with current accumulation and exchange fluids (molten salts are generally adopted and the max temperatures are generally below 600 °C), even if other solutions have been suggested that reach 800 °C. An innovative solution based on liquid lead has been proposed in an ongoing experimental project named Nextower. The Nextower project aims to improve current technologies of the solar sector by transferring experience, originally consolidated in the field of nuclear plants, to accumulate heat at higher temperatures (T = 850–900 °C) through the use of liquid lead heat exchangers. The adoption of molten lead as a heat exchange fluid poses important criticalities of both corrosion and creep resistance, due to the temperatures and structural stresses reached during service. Liquid lead corrosion issues and solutions in addition to creep-resistant material selection are discussed. The experimental activities focused on technical solutions adopted to overcome these problems in terms of the selected materials and technologies. Corrosion laboratory tests have been designed in order to verify if structural 800H steel coated with 6 mm of FeCrAl alloy layers are able to resist the liquid lead attack up to 900 °C and for 1000 h or more. The metallographic results were obtained by mean of scanning electron microscopy with an energy dispersive microprobe confirm that the 800H steel shows no sign of corrosion after the completion of the tests.

Микротопохимия конкреций пирита в кремнистых алевропелитах Юбилейного медноколчеданного месторождения (Южный Урал) по данным LA-IСP-MS

Object . The zonal pyrite nodules and metacrystals from siliceous siltstones of ore-bearing horizon of the Second ore body from the Yubileynoe massive sulfide deposit are studied. Materials and methods . We used 9 samples and 15 polished sections of siliceous siltstones with pyrite mineralization. Analysis of chemical composition minerals was determined by Tescan Vega 3 with an energy dispersive microprobe Oxford Instruments X-act (Institute of Mineralogy UB RAS, Miass). Quantitave LA-ICP-MS analysis of pyrite for major and trace elements was carried out using New Wave Research UP-213 laser microprobe coupled to an Agilent 7500 quadrupole ICP-MS housed (University of Tasmania, Australia). Results. Microtopochemistry was established that the diagenetic core of the nodule is characterized by trace elements of typical poikilites of quartz (Si) and alumosilicates (Si, Al, Mg, V, Cr, K, Na, Ca), rutile and titanite (Ti), inclusions of chalcopyrite (Cu), sphalerite (Zn), galena (Pb, Sb, Bi), tetrahedrite-tennantite (As, Sb), native gold, petzite, hessite (Au, Ag, Te), tellurobismuthite, altaite, and coloradoite (Te, Bi, Pb). Cobalt and Ni substitute for Fe 2+ . The rim of subhedral pyrite is depleted in most trace elements except for Ni and As. Subhedral pyrite became rich in chalcophile (Au, Ag, Sb, Bi, Cu, Zn, Hg) and lithophile (Ca, K, Na, Cr) elements at the final stage of growth of the nodule. Similar mineralogical and geochemical zonation is typical of the pyrite metacrystals, where a micro-grained core concentrates Pb, Bi and Te, and a rim of subhedral pyrite is depleted in most trace elements. Similarly to the nodules, the outer rim of pyrite metacrystals is enriched in most trace elements (Pb, Au, Ag, Sb, Cu, As, Mo, Cr, etc.). The nodules and metacrystals were formed from diagenetic micronodule of poikilite pyrite. Conclusions. It is suggested that mineralogical and geochemical differences in pyrite metacrystals and nodules are caused by the greater degree of development of rims of subhedral pyrite.

Atmospheric pressure non-equilibrium plasma cleaning of 19th century daguerreotypes

In the work, the feasibility of using atmospheric pressure non-equilibrium plasmas to clean the surface of a deteriorated 19th century daguerreotype has been examined and a proof-of-principle demonstration is given. The daguerreotype was treated by means of both a commercial plasma jet source (kINPen 09, Neoplas Tools GmbH) and a specially designed Dielectric Barrier Discharge (DBD) plasma source operated within a controlled volume at atmospheric pressure, by using a argon-hydrogen gas mixture (H2 content: 35% vol.) to remove corrosion products, without immersion of the substrate in solvents or chemicals. The effectiveness of plasma treatment in removing tarnishing products while preventing damage to the fragile image has been evaluated analysing the surface by means of scanning electron microscopy (SEM) with energy dispersive microprobe (EDS) for localized elemental analysis, micro-Raman and ATR-FTIR spectroscopy for phase identification.

Investigation about ancient mortars and plasters in the Mondovì cathedral (Cuneo, Italy)

St. Donato Cathedral of Mondovi (Cuneo Province, North-West Italy) is the last project of the famous architect Francesco Gallo (1672-1750). The construction started in 1744, but it has been consecrated only in 1763. The building is an impressive brick-made church with a main nave and two lateral aisles, which remarkable length is 56 meters and it is 24 meters wide. Its style is mainly baroque with some neoclassical additions. After the edification, the decoration of the interior walls was very simple; probably it was a white finish of smooth plaster consisting of lime and magnesian lime mortar. There are some evidences of a basic decoration: a uniform bluish or grayish tinge. Around 1850 a plan for a new decorative apparatus was made and some of the most important painters of that period were committed to paint sacred subjects on the vault and apse, and to provide the decorations of the walls. In early 2012 started some important restoration works in the Cathedral. One of the main purpose of the Restoration Team is to get scientific and historical information about the work of ancient painters and decorators. The scientific investigation on mortar layers was conducted on various samples, several of them were resin included polished sections, using Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) supported by Energy Dispersive Microprobe spectroscopy (EDS). The analyses carried out on the samples clearly showed the historical stratifications of different layers. The first stratification is made of mortars and plasters dating around the middle of 18th century, and shows different compositions and very neat layers. While the last stratification is a more recent mortar plaster, which is coarse-grained, used as a background for the new decorations done in the middle of 19th century.

The Gd–Ni–Al system: Phases formation and isothermal sections at 500 °C and 800 °C

Phase relations in the Gd–Ni–Al ternary system have been established for two isothermal sections (500 and 800 °C) based on X-ray powder diffraction analysis (XRD), Light Optical Microscopy (LOM), Scanning Electron Microscopy (SEM) coupled with Energy dispersive Microprobe Analysis (EPMA) on about 31 annealed alloys in the 50–100 at.% Al region. Seven intermetallic phases have been identified in samples annealed at 500 °C and 800 °C: Gd3Ni5Al19 (oS108–Gd3Ni5Al19), Gd4Ni6Al23 (mS66–Y4Ni6Al23), GdNiAl4 (oS24–YNiAl4), GdNiAl3 (oP20–YNiAl3), Gd3Ni7Al14 (hP72–Gd3Ni7Al14), GdNiAl2 (oS16–CuMgAl2) and GdNi2Al3 (hP18–GdNi2Al3). One additional ternary phase GdNi3Al9 (hR78–ErNi3Al9) has been found only in samples annealed at 800 °C. The isothermal sections have been determined and then compared, the crystal structures of the ternary phases have been confirmed and lattice parameters calculated.

Characterization of secondary arsenic-bearing precipitates formed in the bioleaching of enargite by Acidithiobacillus ferrooxidans

The purpose of this study was to characterize secondary minerals that were formed in the bioleaching of enargite (Cu 3AsS 4) by Acidithiobacillus ferrooxidans. Two parallel cultures were used: one was adapted to arsenic in the growth medium and the other was wild-type. The progress of the solubilization of As in A. ferrooxidans cultures was stepwise and different from that observed in the non-adapted culture. In contrast, the bioleaching of Cu and Fe from enargite was not affected by prior adaptation of the culture. Minor presence of jarosite was observed by X-ray diffraction (XRD) in solid residues after the bioleaching, and no other peaks of secondary crystalline minerals were detected. The relative intensities of As 3d and Fe 2p to Cu 2p in X-ray photoelectron spectroscopy (XPS) for the solid residues were at maximum at 46 days after the bioleaching with As-adapted A. ferrooxidans. The results from the examination of solid residues with XPS, transmission electron microscopy with energy-dispersive microprobe (TEM-EDS) and XRD after 46 days of contact with As-adapted A. ferrooxidans showed the presence of metastable, amorphous ferric arsenate as an intermediate on the surface of enargite and minor amounts of jarosite. The amorphous ferric arsenate phase did not appear to have an adverse effect of the dissolution of Cu from enargite.

Analysis of Mn-bearing lawsonite occurring in meta-siliceous rocks in Hakoishi serpentinite mélange of Kurosegawa Belt, Central Kyushu, Japan

Mn-bearing lawsonite was discovered in meta-siliceous rocks metamorphosed under the lawsonite-blueschist facies formed at less than 350 °C and 0.8-1.0 GPa in the Hakoishi serpentinite melange of the Kurosegawa Belt, Central Kyushu, Japan. The lawsonite deposits were accompanied by those of hematite, braunite (Mn2+Mn63+SiO12), and quartz, indicating that the rock had metamorphosed under high Oxygen fugacity (fO2) (∼ -20 < log fO2 < -5) at the abovementioned P-T conditions. The Oxygen fugacity led to the conversion of all the iron into ferric compounds and some of the manganese into its trivalent form. As a result, the lawsonite was found to contain a significant amount of (Mn3+ + Fe3+), substituting ∼ 5-11 mol% of Al in the ideal lawsonite formula. Lawsonite in meta-siliceous rocks metamorphosed under low fO2 state (∼ log fO2 < -20), and metabasites collected from the same melange contained lesser amount of (Mn3+ + Fe3+), substituting ∼ 3-5 mol%. The amount of Sr and Ba in the analyzed lawsonite were below the detection limit of energy-dispersive microprobe analysis, ∼ <0.1 wt%. This indicated the existence of an unknown endmember of the lawsonite group of minerals, CaFe23+Si2O7(OH)2·H2O or CaMn23+Si2O7(OH)2·H2O on the basis of the observed substitution. The extremely high fO2 state that results in the conversion of all the iron into ferric compounds along with the Mn-rich local chemical compositions would necessarily enhance (Mn3+ + Fe3+) ⇔ Al substitution in lawsonite.

Stratigraphic condensed deposition and diagenetic evolution of green clay minerals in deep water sediments on the Ivory Coast–Ghana Ridge

Green grains concentrations were studied through the 22 m Pleistocene sedimentary column recovered from Ocean Drilling Project Site 959 (in 2100 m water depth) located on a small plateau on the northern flank of the Côte d'Ivoire–Ghana marginal ridge. The green clay material usually fills the chambers of pelagic foraminifers. Taking into account the variance in color and mineralogic composition of the bulk green grains fraction observed in each level, a methodological approach was especially performed: mineralogical and chemical analyses were done successively on the bulk green material, then on hand-picked white, pale green, medium green and dark green grains, and lastly, surface and spot analysis of nanno-structures were obtained using an energy dispersive microprobe coupled with a scanning electron microscope. Green grains concentrations are evidenced showing both rising up of green/white ratio and increasing abundance of cracked dark green grains. These irregular concentrations are not consistent directly with a general climatic forcing as evidenced by δ 18O isotopic curve, but are the result of recurrent bottom-current activity. Thus, winnowing process is the cause of the long lasting ionic exchange and mineralogical evolution at the water sediment interface. Clay infilling composed of smectite (35–40%), kaolinite (45–50%), traces of mica, calcite and quartz was a precursor material. Along with dissolution of kaolinite, crystallochemical modifications of smectites were observed both to the sequential concentration scale (bulk samples) and to the individual grain scale (from white to dark green): increment of Fe content associated decrease of Al and increase of layer charge and K content. In the layers with the highest green grain concentrations and in agreement, with crystallochemical formulae, Fe 3+-rich montmorillonite displays octahedral charge, tetrahedral charge appears only when Fe content increased >1.2 Fe per formulae. With the maturation process the growing of the closed layers is observed (mixed layer smectite–glauconite 80/20). Nearly similar evolution patterns were recorded at various levels (0.01, 0.85, 2.2 Ma) of the Pliocene–Pleistocene accumulation, however the nontronite way is evidenced in the lowest green grains concentrations and remind the previously described shelf processes. Independently of the morphologically induced winnowing, in these marine tropical deposits, the glauconitization process was especially favored by abundant iron supply and was not affected by low temperature (∼3°C). It is suggested that in deep-water environment, bottom-current controlled iron deposition and disponibility, strongly influencing the mineralogic evolution. A too lengthy dispersal of iron microparticles played an ultimate role in the development of the montmorillonite way rather than the nontronite way. This would be the most commonly found in shallow-water environment.

Identification of coarse dispersoids in AlLiCuMgZr alloy

The submicrometre dispersoids containing iron in the aged AlLiCuMgZr alloy have been investigated by transmission electron microscopy combined with energy dispersive microprobe analysis. The dispersoids were identified as monoclinic Al 3Fe phase. They grow as elongated plates or may appear as randomly shaped particles. They are not single crystals but consist of two (or more) small grains, thus exhibiting complex selected area diffraction patterns owing to the superposition of several reflecting zones arising from different grains.

Application of copper conductor and ruthenium containing oxides-glass resistor to high-frequency hybrid ICs for a portable cellular radio

An assessment of a copper-conductor and resistor system and its performance in a high-frequency hybrid application is presented. Resistance of the copper compatible resistor, containing RuO/sub 2/, increases after refiring over 600 degrees C and drastically increases as the firing temperature is raised. Scanning-electron-microscope and energy-dispersive microprobe analyses revealed the existence of a RuO/sub 2/-poor area in the resistor adjacent to the copper terminals. The resistivity in this area is higher than that in areas removed from the terminals, and it increased with the refiring temperature. These facts indicate that the resistance change is caused by the diffusion of Ru to the copper conductor. Various approaches were taken to minimize this phenomenon. The most effective was insertion of a conductor pad between the copper conductor and resistor. Resistors with this type of Ag-Pd conductor pad meet the various requirements for practical application of hybrid ICs. Based on these results, a prototype, high-frequency hybrid IC (voltage-controlled oscillator, VCO) was fabricated.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Cellular and mitochondrial changes induced in the structure of murine skeletal muscle by crotoxin, a neurotoxic phospholipase A 2 complex

Following a single i.m. injection of a sublethal dose of crotoxin into the hindlimb of mice, degenerative changes were observed in the soleus muscle in the ensuing 72 hr using light and electron microscopy. A similar degree of myonecrosis resulted from the injection of the phospholipase A 2 subunit alone, whereas crotoxin reconstituted from a chemically modified phospholipase A 2 subunit with low catalytic activity showed weak myonecrosis and the non-enzymic subunit, crotapotin, was inactive. Visible defects of the sarcolemma were associated with underlying necrotic areas and attraction of macrophages. Internally, hypercontraction bands were often present and mitochondria in the rounded, orthodox configurational state contained linear dark bodies as part of their cristal organization. In fibre segments with slow onset of degeneration, many mitochondria additionally contained clusters of electron opaque deposit and in mitochondria, heavily laden with such deposits, energy-dispersive microprobe analysis showed the presence of a high concentration of calcium. It was concluded that the primary site of action of crotoxin was hydrolysis of the sarcolemmal membrane and that mitochondrial changes were associated with calcium accumulation in response to an altered internal environment. Regeneration of fibres was rapid.

A Combined Dilution and Line-Overlap Coefficient Solution for the Determination of Rare Earths in Monazite Concentrates

The rare earth elements (REE) together give guite complex X-ray emission spectra with a considerable number of overlaps at analytical energies by lines of other REE with lower atomic numbers. Where the concentration of REE is high, as in lanthanide minerals, this Interference is more difficult to rectify. Smith and Gold resolved a similar problem with lower atomic number elements in energy dispersive microprobe analysis by establishing a series of overlap coefficients. They asserted that accurate corrections were necessary because of the relatively poor overall resolution of the instrument and that these should not be limited to the major coincidences. Some of the smaller values had probably been ignored because they were considered statistically Insignificant. The mathematical matrix of Smith and Gold covered 22 elements from fluorine to barium, with intensity coefficients (other than intraelement) quoted from 0.01% to 282.1% and with ZAF corrections necessary in cases of K to L conversion. The overlap coefficients were also adjusted for matrix effects.

Energy dispersive microprobe analysis of intracellular mineral deposits in rat bone

The use of an energy dispersive X-ray microanalytical system (EDX) attached to a conventional transmission electron microscope (TEM) allows images of good morphological resolution from ultra-thin specimens and spectra of all detectable elements to be obtained simultaneously at radiation doses which are low compared to wavelength dispersive detectors. For reasons of detection efficiency the solid angle subtended from the specimen to the detector is maximised (∼0.l sterad) in our system, a LINK SYSTEMS 290 with a 30mm2Si(Li) crystal fitted to a JEOL JEM lOOC. However, with this type of system the recorded spectrum has contributions not only from the small areas which can be probed but also from scattered electrons, and X-rays originating in the surrounding specimen, the specimen support system and the microscope environment of the specimen. The problem is particularly acute in projects, such as the present, where it is necessary to detect and determine the ratios of elements (Ca and P) in small quantities in close proximity to relatively massive concentrations of the same elements.Modifications to our system have been described (Nicholson et al., 1977a;Biddlecombe et al., 1977) which greatly improve the peak/background ratios for quantitative analysis and eliminate all of the specific peaks of non-specimen origin. For ease of maintenance the JEOL 100C is fitted with thin foil condenser apertures (10μm thick molybdenum) as standard. At the accelerating voltage used in this study (80 keV) a considerable number of electrons are transmitted by these apertures and with the electron probe placed adjacent to fully mineralized bone the scattered electrons were responsible for generation of sizeable Ca and P signals. We have replaced the standard foils with thick (0.25 mm) molybdenum apertures.

A systematic error in energy dispersive microprobe analysis of Ni in steel due to the method of background subtraction

AbstractExperiments and a literature survey both show that energy dispersive microprobe analysis of Ni in steel generally gives substantial negative errors. This situation has been related to significantly lower X‐ray intensity ratios, k values, from an energy dispersive spectrometer system compared with a conventional wavelength dispersive spectrometer. Lower Fe contents in the specimens have been shown to give decreasing errors, which appear to be independent of the ZAF correction calculations.It is suggested that the systematic error for Ni is caused by the method of background subtraction, which seems to reduce the Ni Kα area. The error can be minimized if peak‐height intensities are used and if the background level is measured and subtracted manually.

A Scheme for Fully Quantitative Energy Dispersive Microprobe Analysis

A procedure and program are described for rapid, economical and simple production of fully quantitative, multi-element analyses from energy dispersive microprobe data. Methods are outlined for background shaping and scaling, comprehensive overlap correction, and adjustment for instrumental drift. Program facilities include the output of all coefficients required, built-in standard data, the option to use default standards when no working standards have been measured, and the ability to respecify standards during data processing.

Chemical discrimination of petrographically defined clast groups in Apollo 14 and 15 lunar breccias

Many studies of the diversity of lunar rock types have concentrated on either petrographic (e.g. Wilshire and Jackson 1972a) or chemical (e.g. Reid et al. 1972) classifications. This study was undertaken to investigate the compatability of these approaches and also the range and relationships of rock types in the Imbrium region of the moon. Clasts in breccias and fines from the Apollo 14 and 15 landing sites have been studied with microscopic, energy dispersive microprobe and statistical techniques. On petrographic criteria, seven clast groups can be distinguished: (1) anorthositic rocks, (2) mare basalts, (3) mesostasis-rich non-mare basalts, (4) clasts of monzonitic to granitic composition, (5) metamorphosed basaltic rocks, (6) recrystallized breccias, and (7) glasses. Multiple discriminant analysis and principle component analysis, applied to chemical analyses of the clasts, showed that the clast groups of primary or probably primary origin (1, 2 and 3) are chemically distinct and well defined. However, compositions of clasts of secondary origin (groups 5, 6 and 7) only partly overlap those of the primary groups, suggesting that they may represent mechanical mixtures. The variation between and within the plagioclase-rich clasts from highland areas can be accounted for by an enrichment in a granitic component like group 4, and an enrichment in calcic plagioclase.