Use Of Electron Probe Microanalysis Research Articles

Phase Equilibria in the Ce-Pr-Fe System at 600 °C

The phase relationships of the Ce-Pr-Fe ternary system at 600 °C were experimentally investigated using equilibrated alloys and diffusion junction samples with the use of electron probe microanalysis, x-ray diffraction, and scanning electron microscopy. The isothermal section of the Ce-Pr-Fe system at 600 °C consists of 7 single-phase, 11 two-phase, and 5 three-phase regions. No ternary compound was found. The PrFe2 phase was observed in both ternary alloys and diffusion samples at normal pressure. The solid solubility of Ce in PrFe2 and Pr2Fe17 is 1.76 and 3.75 at.%, respectively. The solid solubility of Pr in CeFe2 and Ce2Fe17 is 13.21 and 0.77 at.%, respectively.

Effect of Yttrium Contents on the Microstructure of a Hot-Rolled Tantalum-Containing 12Cr-ODS Steel

Dual-phase oxide dispersion strengthened (ODS) steels of Fe–12Cr–xY (x=0.1, 0.2 and 0.3 wt%) have been fabricated by casting, hot-forging and subsequent hot-rolling. Microstructure of the hot-rolled samples was carefully characterized by use of electron probe microanalysis (EPMA), electron backscatter diffraction (EBSD) and transmission electron microscope (TEM). The results show that all the samples consist of ferrite phase with coarse fiber grains (elongated along the rolling direction) and martensite phase in the form of fine block grains. As the Y addition increases, the ratio of ferrite to martensite and density of low-angle boundaries (LABs) within the martensite and ferrite grains do not change significantly. The Y2O3 particles introduced by self-oxidation during casting are survived without being dissolved or refined after hot-forging and hot-rolling. However, as the Y addition increases, the Y2O3 particles tend to aggregate with fine M23C6 and TaC carbides. The hardness of the sample with high Y additions is lower than that of the samples with none or low Y additions, which could be attributed to the aggregation coarsening of the yttria and TaC particles, resulting in a decrease in dispersion strengthening effect. The effect of Y additions on microtexture was also discussed.

Features of the X-ray microanalysis (electron probe microanalysis) of nitrogen-containing compounds

The goal of this study is development of the method for studying the chemical composition of natural and synthetic nitrogen-containing compounds using electron probe microanalysis (EPMA) and the use of EPMA for identification of the form of occurrence of light elements (C, N, O) in complex anions and cations. The analysis was performed using K α lines attributed to electronic transitions from valence 2p states to internal 1s states. The characteristic features of the K α spectra of C, N, O, which affect the correctness of the EPMA results were revealed to introduce the corrections that take into account the integrated line intensity, the effect of self-absorption of the nitrogen line and absorption of the background by nitrogen. The method is intended for studying different nitrogen-contained samples including diamonds obtained by detonation synthesis. The surface of these samples is usually covered with a layer oxygen- and nitrogen-containing functional groups. The main problem associated with the experiment is determination of optimal conditions for excitation and registration of K α lines. The accelerating voltage used is 10 kV, the beam current is 50 – 120 nA. In the analysis in the differential mode of recording the signal amplitude we use the same (for all samples) empirical formula to describe the shape of the background intensity curve in the vicinity of the nitrogen line. The resistance of the samples to the impact of the electron beam is increased when using a raster mode with a linear size of 20 – 40 μ m and sample movement within the area ~100 × 100 μ m 2 (if possible with allowance for the sample size). The concentrations of the determined elements were calculated using the PAP program with B. L. Henke absorption coefficients. The detection limits of carbon, oxygen and nitrogen at a current of 80 nA were 0.33, 0.46 and 0.86 wt.%, respectively.

Phase Composition and Microstructure of UHPHT Vein Glass from Giant Diamondiferous Kara Impact Crater by Raman Mapping

2D and 3D Raman mapping allows to observe “in situ” distribution of phases and relationship of minerals in rock samples, different mineral aggregates, mineral inclusions within crystals and other quantitative spectroscopic studies of mineral substances and materials. The method is realized in accumulating and processing of big data array of Raman spectra (RS) from selected areas of a studied sample with subsequent visualization in XY plane at 2D mapping or in the form of 3D experimental models with XYZ coordinates in a case of 3D Raman mapping. During the mapping different analytical data can be visualized as maps such as spatial distribution of mineral phases, degrees of their crystallinity, orientation of crystallites and their size, residual tension in minerals and inclusions and many other parameters. As 3D Raman mapping demands higher requirements to quality of samples, takes significantly long time expenditure and big data for processing, 2D Raman mapping looks to be the most effective for different mineralogical applications. In this work we demonstrate advantages of 2D Raman mapping on the example of studying of the impact ultrahigh-pressure high-temperature (UHPHT) vein glasses with melt-crystallized ultrahigh-pressure silica phase – coesite, for the first time found within diamondiferous impactites of the giant Kara meteorite crater. The mapping was produced with processing of typical spectra ranges of recognized mineral phases met in analyzed areas. As a result of the conducted studies it has been established what according to spectroscopic data coesite hangs to central parts of UHPHT silica glass located in general matrix of aluminosilicate glass. The sites of silicate glass are characterized by fully amorphous state that is obviously shown in its typical ranges. The areas with a high luminescence correspond to inclusions of smectite micro-drops in UHPHT silica glass isolations that has been confirmed with the accompanying study with use of electron probe microanalysis (EPMA), energy dispersive spectroscopy (EDS) and electron diffraction (ED). The used 2D Raman mapping to the impact vein glasses of the Kara meteorite crater allowed to reveal distribution of mineral phases in UHPHT glass, showing distribution of amorphous and crystalline phases that is undoubted advantage of the Raman spectroscopy. In full text of the paper technical features of Raman 2D mapping are shown that can be useful for similar mineral objects and materials with complex phase structure and different degree of ordering.

You Do What in Your Microprobe?! The EPMA as a Multimode Platform for Nitride Semiconductor Characterization

While the use of electron probe microanalysis (EPMA) is widespread in the geological and metallurgical sciences, it remains less prevalent in the field of semiconductor research. For these materials, trace element (i.e. dopant) levels typically lie near or beneath the detection limit of wavelength-dispersive Xray (WDX) spectrometers, while alloy compositions of ternary mixtures and multilayer structures can more readily be determined using X-ray diffraction techniques. The electron beam measurements more commonly applied to semiconductors remain transmission electron microscopy (for structural characterization), and scanning electron microscopy (topographic, optical and electrical information). Despite this, there are many aspects of the EPMA that make it an attractive platform for all of thesetypes of semiconductor characterization, particularly when combining compositional information fromWDX with complementary and simultaneously-acquired signals. These advantages include: built-inlight optics; a stable, quantified and high-current beam; and a combined large-area and high-resolutionmapping capability. This allows the measurement of cathodoluminescence (CL), electron beam-inducedcurrent (EBIC) and electron channelling contrast imaging (ECCI) signals alongside WDX, which weapply to the investigation of visible and UV AlxInyGa1-x-yN materials, devices and nanostructures.

Quantification of the level of samarium/barium substitution in the Ag-Sm1+xBa2−xCu3O7−δ system

The high-temperature SmBa2Cu3O7−δ (Sm-123) superconducting system, which is characterised by a high critical transition temperature (Tc) and a high critical current density (Jc), suffers severely from the effects of Sm/Ba substitution in the superconducting Sm-123 phase matrix, and especially so for large, single grains grown in air, resulting in a significant variation in Tc at different positions within a single grain. As a result, the suppression of Sm/Ba substitution in the Sm1+xBa2−xCu3O7−δ phase matrix (SmBCO, where x represents the Sm/Ba substitution level in the SmBCO system) is critical to achieving good superconducting properties in this material. Here we report the use of Electron Probe Micro-Analysis (EPMA) to investigate, adjust and optimise the composition of mechanically-stabilised standard Ag-SmBCO bulk single grains. We show that the substitution levels within these samples changes linearly within increasing distance from the vicinity of a single crystal seed used to nucleate the single grain growth process. In addition, we identify a constant value of x of −0.080 for the composition-adjusted Ag-SmBCO bulk single grain. This is the first time that the quantification of the Sm/Ba substitution level in the SmBCO system has been measured accurately and directly using EPMA, and suggests clearly that the Sm/Ba substitution can be suppressed effectively in air. This research will provide significant insight into the development of a process to suppress Sm/Ba substitution even further in superconducting SmBCO single grains in the future.

Isothermal sections of the Co-Nb-Ni phase diagram at 1200 and 1375 K

The isothermal sections of the Co-Nb-Ni system were constructed at 1375 K and 1200 K by investigations of equilibrated alloys with the use of electron probe microanalysis (EPMA), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD) and differential thermal analysis (DTA). In the Co-Nb-Ni system, phases take part in the following three-phase equilibria: (α+γ+λ), (α+λ+μ), (γ+λ+λ′) at 1375 K and (α+γ+λ), (α+λ+μ), (α'+γ+λ) at 1200 K. The α′-phase of the binary Co-Nb system at 1200 K has the composition Co3Nb and crystallises with the Mg3Cd-type of the crystal structure.

The use of electron probe microanalysis and laser ablation-inductively coupled plasma-mass spectrometry for the investigation of 8th–14th century plant ash glasses from the Middle East

This is the first broad survey using major, minor and trace element analyses of 8th–15th AD plant ash glass from the Middle East across a 2000mile area stretching from Egypt to northern Iran. This was part of the ancient Silk Road that extended from the Middle East, through central Asia to China. Up to now, some compositional distinctions have been identified for such glasses mainly using major and minor element oxides and radiogenic isotopes. Our new trace element characterisation is for such glasses, mainly found in selected cosmopolitan hubs, including one where there is archaeological evidence for primary glass making. It provides not only far clearer provenance definitions for regional centres of production, in the Levant, northern Syria and in Iraq and Iran, but also for sub-regional zones of production. This fingerprinting is provided by trace elements associated with the primary glass making raw materials used: ashed halophytic plants and sands. Even more surprising is a correlation between some of the sub-regional production hubs and the types of glass vessels with diagnostic decoration apparently manufactured in or near the cosmopolitan hubs where the glass was found such as colourless cut and engraved vessels (in Iraq and Iran) and trail-decorated vessels (in the Levant). This therefore provides evidence for centres of specialisation. Our trace element characterisation provides a new way of defining the Silk Road by characterising the glass that was traded or exchanged along it. Taken together this data provides a new decentralised model for ancient glass production.

On the Thermodynamics and Kinetics of TCP Phase Precipitation in Re‐ and Ru‐ Containing Ni‐base Superalloys

AbstractThree experimental Ni‐base superalloys of the second, third and fourth generation are studied in this work to clarify the effect of Re and Ru on the precipitation of TCP phases. Thermodynamic calculations using the CALPHAD method are performed based on the local chemical composition obtained with the use of electron probe microanalysis. The effects of microsegregation and γ′‐precipitation are taken into account. The results, complemented with scanning electron microscopy observations, show that Re increases, while Ru decreases the inclination of the material to precipitate TCP phases. The effect of both elements is assigned to thermodynamic rather than kinetic reasons. The CALPHAD‐calculations do predict the effect of Re on the TCP phase formation in the investigated alloys correctly, but not the effect of Ru.

Uncertainty and capability of quantitative EPMA at low voltage – A review

The use of electron probe microanalysis (EPMA) at low voltage allows improvements in the lateral resolution and surface sensitivity of the technique down to the sub-micrometre scale, and it is also useful in minimizing X-ray absorption (for the analysis of ultra-light elements), charging effects and secondary fluorescence. However, EPMA at low voltage is accompanied by a number of problems which may affect the accuracy of quantitative results. A large number of these problems arise from the need of using low-energy X-ray lines such as L- and M-lines, which have low fluorescence yields, large uncertainties in the mass attenuation coefficients, and are affected by several spectroscopic difficulties (e.g., peak shifts and overlaps). Other factors that play an important role at low voltage are carbon contamination, surface oxidation, the quality of sample polishing, the influence of a conductive coating and the limitations of matrix correction procedures. In this paper, we illustrate the capabilities of EPMA at low voltage and we examine in detail the different sources of uncertainty that may affect the accuracy of quantitative results.

Processing of electron microprobe data from the analysis of altered cementitious materials

The purpose of this paper is to present a method for processing electron microprobe data coming from the analysis of degraded cementitious materials. The application domain is that of cement matrices exposed to attack by aggressive media inducing the leaching of one or more chemical elements from the cement paste — typically attacked by neutral or acid aqueous environments. As raw data obtained from electron probe microanalysis (EPMA) come in the form of relative quantities of elements, the aim of the processing is to obtain the absolute variation of the specimen's chemical composition in the degraded zone and consequently to allow a better understanding of the degradation mechanisms by the aggressive environment under consideration. This method was designed for degraded specimens in which the porosity was not filled with resin before the EPMA. The method uses the titanium content of the cement matrix as a control, this element being stable during attack by neutral or acidic media. The method is described in detail using the example of the attack of cement pastes by a mix of several organic acids (notably acetic acid) at pH 4. The use of EPMA for sound and altered cement pastes is also validated. The application domain of the correction method is discussed.

Trace element characterization of medieval and post-medieval glass objects by means of INAA and EPMA

Instrumental neutron activation analysis (INAA) was applied to create a database for minor and trace elements in medieval and post-medieval glassware in order to establish a methodology for estimating the origin of the glass objects. First, general characterization of glass types was done on the basis of the results obtained by the use of electron probe microanalysis (EPMA). Information received by the use of INAA provided the additional valuable data reflecting to some extent the method of preparation or the differentiation of various sources of certain raw materials. Several glass samples and a set of various reference glass materials were used for our experiments.

The Determination of Copper Composition Profiles in Semiconductor Device Aluminum Interconnect Electromigration Test Lines using Electron Probe Microanalysis (EPMA)

Extensive long range transport of copper has been observed in polycrystalline aluminum-copper (Al-Cu) interconnects subjected to accelerated electromigration testing. Cu depletion is believed to be the rate limiting factor for electromigration damage accumulation. It is not clear if this is also the case for Al-Cu interconnects with bamboo/near-bamboo microstructures. In order to understand this phenomenon, Cu transport under electromigration conditions in bamboo microstructures has to be characterized quantitatively. This paper describes the procedure used to determine Cu distributions on a series of bamboo test structures subjected to accelerated electromigration (EM) testing. Copper composition profiles were determined for these structures through the use of electron probe microanalysis (EPMA) techniques and customized corrections for non-standard interaction volumes.Aluminum (0.5 wt.% Cu) interconnect test line structures were fabricated with four metal layers and surrounding silicon dioxide dielectric. Following EM testing, the samples were deprocessed to expose the test lines at metal layer three, as shown in Figure 1.

An inter-laboratory comparison of the electron probe microanalysis of glass geochemistry

Abstract Tephrochronology commonly relies upon grain-discrete analysis of glass shards to reveal the subtle geochemical differences between tephras from past explosive volcanic eruptions. The use of electron probe microanalysis for this purpose is widely accepted by tephrochronologists. It is widely recognised that both precision and accuracy must be maximised, and that rigorous standardisation procedures must be followed. In this paper the performances of seven northern European electron microprobe centres are compared, using a geochemically homogeneous obsidian secondary standard. The results reveal that a number of tephra-oriented probe centres could benefit from exercises similar to the programme outlined within. In particular, it is evident that a number of these centres undertaking tephrochronological investigations have generated geochemical data that may be inadequate in terms of distinguishing between tephras. Inaccuracy in the determination of sodium is seen to be the main difficulty. In recent years the application of distal tephrochronology to stratigraphical problems in the northern European Quaternary record has become increasingly common. Geochemical standardisation is essential at an early stage in the development of a regional tephrochronological framework and, we hope, exercises such as presented here will encourage the production of reliable tephra geochemical data.

A determination of the chromium concentration for ‘healing’ layer formation during the oxidation of chromium-depleted 20cr-25ni-nb stainless steel

High temperature oxidation tests have been performed at 973–1123 K in a CO 2 based gas on specimens of 20Cr-25Ni-Nb stainless steel in which the surface chromium concentration was reduced by prior vacuum annealing at 1273 K. It is shown that the rapid initial oxidation rate decreases as a result of the formation of a chromium-rich ‘healing’ layer at the oxide-metal interface. For oxidation temperatures ≥ 1073 K, a chromia-type layer readily forms whereas lower oxidation temperatures favour the formation of a chromium-rich spinel after considerably longer oxidation times. Use of electron probe micro-analysis to determine the pre-existing chromium depletion profile and measurements of the depth into the steel at which this ‘healing’ layer forms enable an assessment to be made of the chromium concentration necessary to form this layer. This concentration increased from 15.2 w/o at 1123 K to ≥ 18.5 w/o at 973 K.

Factitial cutaneous ulcers and nodules: The use of electron-probe microanalysis in diagnosis

Two cases are reported in which persistent nodular or ulcerative skin lesions with granulomatous histology suggested possible injection of foreign material. Electron-probe microanalysis was used to determine the presence and nature of foreign materials present in the skin. This technic identified specific agents used as fillers in tablets, indicating the injection of pulverized tablet material. The patients were counseled regarding this evidence, and psychotherapy and drug rehabilitation were recommended in each instance. This technic provides a valuable tool for accurate identification of foreign substances in the skin.

Some Factors Influencing the Sintering Behaviour of Austenitic Stainless Steel Powders

AbstractDensification studies of sintered stainless steel powder blends have shown that the introduction of delta-ferrite into the micro structure increases substantially the sintering rate of the compact. Model experiments, in which spherical particles of a 316 powder were sintered on several different base plates including iron, 18Cr–12Ni stainless steel, iron–12% nickel, have been carried out to provide more detailed information. Quantitative observations have been made on the rate of neck growth and on the compositional gradients which develop between particle and plate. It has been found that the sintering rates were very sensitive to the composition of the base plate and to the presence of austenite/ferrite interfaces. Micro-examination and the use of electron probe microanalysis indicate that interdiffusion of elements between particles and plates is by both surface and volume diffusion.

The dissolution of grain boundary allotriomorphs

Concentration contours round dissolving grain boundary allotriomorphs in the systems Al-Cu and Al-Ag have been determined by the use of electron probe microanalysis. It was found that the shape of the contours is dependent only on the homologous temperature, and not on axial ratio of the allotriomorph, degree of supersaturatiou or absolute temperature. Above a homologous temperature of 0.93 dissolution is completely dominated by volume diffusion. The grain boundary diffusion contribution was found to increase with decreasing temperature and below a homologous temperature of 0.77 there is extensive grain boundary diffusion before volume diffusion could be detected. These experimental results were fully explained using a theoretical calculation of the relative grain boundary and volume diffusion contributions to dissolution.

A review of some industrial applications of microanalysis

The industrial applications of electron probe microanalysis (EPMA) are first discussed in general terms. When the techniques became commercially available to industry some 12 years ago, most of the applications were concerned with qualitative analysis only. However, during the past 10 years considerable progress has been made in quantitative analysis. The accuracy of this procedure is still a matter of debate and examples are cited of work carried out to determine the cause of various errors, notably from metallurgical studies. Most of the review, however, is concerned with specific examples which illustrate some of the many diverse applications of EPMA. These include (a) identification and origin of non-metallic inclusions in steel, (b) identification of impurities in pottery, (c) use of EPMA in phase diagram work, (d) distribution of elements in chrome ore magnesite brick, (e) biological applications as exemplified by the detection of inorganic substances in tissues, (f) forensic applications as illustrated by the elemental analysis of two samples of paint in a car accident, (g) use of EPMA in the field of electronics and (h) segregation studies on metals. It is emphasized that in many of the examples chosen, EPMA was the only really practicable technique. Les applications industrielles de l'analyse par microsonde à rayons X (EPMA) sont tout d'abord discutées en termes généraux. Lorsque ces techniques furent disponibles commercialement à l'industrie, voici une douzaine d'années, la plupart des applications se limitèrent à l'analyse qualitative. Cependant au cours de ces dix dernières années, des progrès considérables ont été réalisés dans le domaine de l'analyse quantitative. La précision obtenue par cette procédure est encore sujette à débats et un certain nombre d'exemples de travaux poursuivis en vue de déterminer les différentes causes possibles d'erreurs sont mentionnés, en particulier des études métallurgiques. La plupart de cette revue, toutefois, concerne spécifiquement quelques-unes des diverses applications de l'EPMA. Elles comprennent: (a) l'identification et l'origine d'inclusions non-métalliques dans l'acier, (b) l'identification d'impuretés dans la poterie, (c) l'utilisation de l'EPMA dans des travaux sur les diagrammes de phase, (d) la répartition de différents éléments dans des briques de chromite-magnésie, (e) la détection de substances minérales dans les tissus illustrant une des applications biologiques, (f) des applications d'expertises judiciaires telle que l'analyse chimique d'éléments dans deux échantillons de peintures provenant d'un accident de voiture, (g) des applications de l'EPMA dans l'électronique et (h) dans l'étude de la ségrégation dans les métaux. L'attention du lecteur est attirée sur le fait que, dans la plupart des exemples choisis, l'EPMA était la seule méthode réellement pratique. Industrielle Anwendungsmöglichkeiten der Elektronensonden-Mikroanalyse (EPMA) werden allgemein besprochen. Als vor 12 Fahren diese Instrumente für die Industrie erwerbbar wurden, waren es hauptsächlich qualitative Bestimmungen, die damit durchgeführt wurden. Aber während der letzten 10 Fahre zeigten sich in der quantitativen Analyse beachtliche Fortschritte. Die Präzision dieser Verfahren steht noch zur Debatte, und es werden einige Arbeiten—besonders metallurgische—zitiert, welche die Fehlerquellen feststellen. Der Hauptteil dieser Besprechung befaβt sich jedoch mit Beispielen, welche die vershiedenen Anwendungsmöglichkeiten der EPMA darstellen. Unter anderen werden angefürt (a) die Identifizierung und der Ursprung nicht metallischer Stahleinschlüsse, (b) die Identifizierung von Verunreinigungen in Steingut, (c) herstellung von Zustandsdiagrammen, (d) Verteilung der Elemente in Chromerz-Magnesitziegeln, (e) biologische Anwendungen zum Nachweis anorganischer Gewebsbestandteile, (f) gerichtliche Anwendungen wie zum Beispiel eine Elementenanalyse zweier Autolackproben von einem Vekehrsunfall, (g) die Anwendung von EPMA in der Elektronentechnik und (h) Seigerungsuntersuchungen bei Metallen. Es wird betont, daβ bei vielen Untersuchungen EPMA das einzig wirklich brauchbare Verfahren war.