RAPIDviewer is a newly developed ImageJ macro script that addresses the limitations of the indexing program RAPID (which enables the indexing of zone-axis electron diffraction patterns from cubic materials) by generating graphical overlays on the experimental patterns, including configurable spot and Kikuchi line drawings. Additional features include orientation sketches, inverse-pole-figure markers and an option for VESTA file export. Examples utilizing selected-area electron diffraction patterns from an austenitic steel, an M23C6 precipitate and an aluminium alloy illustrate the features of the program.

[This corrects the article DOI: 10.1107/S1600576724004333.].

Precision glass molding is an economical and resource-efficient method for manufacturing precision optics in a replicative way, offering advantages over conventional manufacturing methods, particularly for complex geometries. However, challenges arise due to different thermal expansion coefficients between the mold and the glass, which lead to shape deviations during the cooling process and require high compensation efforts. This study investigates the machining behavior during ultra-precision grinding of an innovative MAX phase composite whose coefficient of thermal expansion can be specifically adapted to that of glass. The aim is to evaluate the influences of varying process parameters and material configurations on surface integrity and the suitability of ultra-precision grinding for mold manufacturing in the context of precision glass molding. Systematic grinding tests were carried out and complemented by force measurements. The resulting surfaces were characterized using optical measurement technology and atomic force microscopy; in addition, the edge zone was analyzed using transmission electron microscopy. The results confirm the basic suitability of ultra-precision grinding for the MAX phase composite but point to potential subsurface damage that could limit its usability in precision glass molding.

This study re-evaluates the selected area electron diffraction (SAED) patterns and electron energy-loss spectrum (EELS) presented by Shumilova et al. ( https://doi.org/10.1134/S1028334X11110201 ), who have reported that they have found natural hexagonal 2H diamond in samples from the Kumdykol (Kumdy-Kol) diamond deposit. A thorough re-evaluation of the original SAED data indicates that a diffraction pattern previously attributed to monocrystalline 2H diamond is, with a very high degree of certainty, not the claimed phase, since it exhibits a much stronger resemblance with the calculated pattern of a high-pressure phase of 2H graphite, and even more with the pattern of a cubic, high-pressure form of silicon carbide. Due to the absence of EDX data, the question regarding the precise composition of this crystalline species could not be conclusively resolved. Furthermore, a second SAED pattern, previously interpreted as a 3C–2H diamond intergrowth, was found compatible with a topotactic 2H graphite–3C mineral association, known as ‘diaphite’, or with sp3-bonded polytypes (3C–2nH, n = 2, 4). A carbon core-loss EEL spectrum, which was used in Shumilova et al. (Dokl Earth Sci 441:1552–1554, 2011) to confirm the presence of 2H diamond, was found to match with that of the 3C diamond structure. While these results do not rule out the natural occurrence of 2H diamonds in general, the re-assessment of the in Shumilova et al. (Dokl Earth Sci 441:1552–1554, 2011) published SAED and EELS data provides no concrete evidence for the presence of monocrystalline 2H diamond in the earlier examined specimens from the Kumdykol site. A correction of the in Shumilova et al. (Dokl Earth Sci 441:1552–1554, 2011) made claims is therefore of significance, to avoid further bias in the ongoing discussion on the nature of the mineral lonsdaleite.

During laser beam welding of metals, process emissions are generated above the workpiece surface, through which the incident laser beam passes. One part of the process emissions are particles which arise from the hot metal vapor phase and agglomerate to form larger chains until they have cooled down completely. Depending on the chemical composition and size of this material emissions, the light waves are reflected, absorbed or scattered to varying degrees. The Mie theory comprehensively describes the scattering and absorption behavior of particles and essentially covers the welding plume produced during laser beam welding with a few assumptions. To specify these assumtions in more detail, this study analyzes the nanoparticles deposited on a glass carrier in the beam path of the laser. The deposition shows prismatic and octahedral structures in the scanning electron microscope, besides the predominantly spherical particles. In a vacuum and therefore with a reduced oxygen content, the ammount of emissions of the keyhole decreases and particles collected in the plume are identified as solid solution bcc-type particles containing Cr, Cu, Fe, Mn, and Ni. In atmosphere at 1000 mbar however, complex solid solutions phases with diffraction patterns compatible to spinel-type NiCr2O4 and NiFe2O4 are formed.

This study presents a new efficient method for determining the 2D unit cell size from HAADF STEM images using angle-resolved lattice population density (ALPD) plots. The approach uses the maxima in these plots, which represent the lines with the highest atom peak density, to determine the cell angle of the primitive 2D unit cell. Lattice types and 2D unit cell sizes that comply with crystallographic standards can easily be obtained by introducing angle constraints for the selection of the ALPD maxima. The method is very flexible and can be applied to images with fewer than 20 atom peaks, making it valuable for the automated analysis of periodic lattices in both large and small crystalline regions. The method has been evaluated for ideal and disordered lattices and is compared in terms of processing speed and the quality of results with the recently proposed real-space motif extraction method and with the well-established Fourier-based crystallographic image processing method commonly used for this task.

A DigitalMicrograph® script RAPID-DM (RAtio method Pattern InDexing) has been developed, which allows instant on-site indexing of zone axis electron diffraction patterns of cubic lattices using the Rn ratio principle. In addition to indexing spot electron diffraction patterns, the program is also capable of indexing Kikuchi patterns taken from or near a zone axis. Both cases are demonstrated by examples for silicon. The program has a guided workflow and requires only three user-defined lines or Kikuchi bands for indexing. RAPID-DM has been extensively tested and verified to work reliably with both calibrated and noncalibrated zone axis patterns and allows the user to easily evaluate whether the material under examination is cubic, pseudo-cubic, or neither. For calibrated patterns, the program provides an average value of the cubic lattice parameter, which can serve for phase identification in connection with a structural database or it can simply be used to verify the material under investigation. In its current state, the developed script has proved to be a valuable add-on to the DigitalMicrograph® platform in the authors' service laboratory, as it greatly simplifies on-site crystallographic analysis of electron diffraction patterns of steels, alloys, and ceramics, which frequently form cubic or pseudo-cubic structures.

A simple paper-based model is proposed, which is based on the right-angle condition for constructive interference of Bragg's law. As demonstrated, the model allows visualization and basic quantification of the geometric relationships between wavelength, lattice spacing, and diffraction angle. Moreover, it facilitates the exploration of the limiting conditions for diffraction, angular dispersion, and the role of wavelength as a factor affecting crystallographic resolution.

Plasma etching is a crucial step in semiconductor manufacturing. High cleanliness and wafer-to-wafer reproducibility in the etching chamber are essential in order to successfully achieve nanometer-sized integrated functions on the wafer. The trend toward the application of more aggressive plasma compositions leads to higher demands on the plasma resistance of the materials used in the etching chamber. Due to its excellent etch resistance, yttrium aluminum garnet Y3Al5O12 (YAG) is starting to replace established materials like SiO2 or Al2O3 in this kind of application. In this study, reactive spark plasma sintering (SPS) was used to manufacture highly dense YAG ceramics from the respective oxides. In addition, yttrium was replaced with heavier lanthanoids (Er, Lu), intending to investigate the role of the A-site cation in the garnet type structure on the plasma erosion behavior. The produced materials were exposed to fluorine-based etching plasmas mimicking the conditions in the semiconductor manufacturing apparatus and the erosion behavior was characterized by atomic force microscopy (AFM), secondary ion mass spectrometry (SIMS), transmission electron microscopy (TEM), and profilometry. The induced chemical gradient in the samples is limited to a few nanometers below the surface, which makes its characterization challenging. For advanced analysis, we developed a correlative characterization method combining SIMS and scanning TEM (STEM)-energy-dispersive spectroscopy (EDS) enabling us to examine the structural and chemical changes in the reaction layer locally resolved. In the case of lanthanoid aluminates, an altered reaction layer and reduced fluorine penetration compared to YAG were found. However, a correlation between the characteristics of the induced chemical gradient and the determined physical erosion rates was not evident. After plasma exposure of highly etch-resistant ceramics such as YAG, a reaction layer with altered chemical and structural composition can be observed. Since this layer is limited to few nanometers below the surface, its characterization is challenging. In the present study we developed a correlative characterization approach that enables a better understanding of the plasma-material interaction. By correlating TEM and ToF-SIMS results, sound conclusions about structure and chemical composition can be drawn. image

As an extension to previous work, the ImageJ macro script RAPID (ratio-method pattern indexing) has been developed to allow instant indexing of calibrated and uncalibrated zone axis aligned electron diffraction patterns of cubic lattices using the Rn ratio principle. The program can be used to index zone axis aligned selected-area electron diffraction patterns, nanobeam electron diffraction patterns, transmission electron microscopy (TEM) Kikuchi patterns and even fast Fourier transforms of high-resolution (scanning) TEM images. The program allows the user to quickly assess whether the material under investigation belongs to the cubic crystal system, is pseudo-cubic or is not cubic at all by adjusting the boundary parameters and allowed errors for lattice indexing. The software also allows one to distinguish between the P, I and F Bravais lattices for certain zone axis directions. For calibrated diffraction patterns, the lattice parameters can be obtained, allowing verification of the material under investigation or phase identification in connection with a structural database. In addition, the program can be employed for determination or verification of the used instrument's camera constant when reference materials are used. Therefore, it is a convenient tool for on-site crystallographic analysis in TEM laboratories.

Commercial purity titanium (cp-Ti) is considered for replacing Ti64 as an implant material in various applications, due to the potential toxicity associated with the release of Al and V ions. However, the mechanical properties of cp-Ti, particularly fatigue resistance, are inadequate for this purpose. In this study, cp-Ti grade 4 rods were processed using a combination of equal channel angular pressing and rotary swaging (ECAP/RS). Tensile and fatigue tests were conducted, along with detailed microscopy and evaluation of corrosion resistance and biocompatibility. An average yield strength of 1383 MPa was obtained while maintaining moderate ductility of 10 %. This represents the highest strength ever recorded for cp-Ti, even exceeding that of Ti64. Additionally, fatigue endurance limit increased by 43 % up to 600 MPa, almost obtaining that of Ti64. Strengthening mechanisms were attributed to the ultrafine-grained (UFG) microstructure generated by ECAP/RS, along with strong crystallographic texture and formation of sub-grain structure. Furthermore, the corrosion resistance and biocompatibility of cp-Ti were largely unaffected, potentially easing regulatory transition in future medical devices. Thus, these results demonstrate high potential of combined ECAP/RS processing to manufacture UFG cp-Ti grade 4 materials that prospectively allow for the substitution of questionable alloys and downsizing of medical implants.

Cubic boron nitride (cBN) is an important material in the cutting and metal processing industries due to its exceptional hardness and high thermal stability, which allows it to withstand temperatures up to 1400 degrees C without decomposing. These properties make cBN and, with that, polycrystalline cBN (PcBN) ideal materials for high-speed machining and other applications, resulting in increased efficiency and reduced costs in production processes. Despite its established importance, the possibility of phase transformations into hexagonal boron nitride phases or partial amorphization during industrial PcBN grinding processes remains unclear and, due to the deteriorated mechanical characteristics, raised recently some concerns about possible losses of cBN 's hardness, wear resistance, and abrasive properties. In order to address this issue and for identifying such potential structural changes, a commercial PcBN grade was exposed to near -industrial grinding process conditions and then characterized in detail by conventional (scanning) transmission electron microscopy (S)TEM and (scanning) electron diffraction techniques. To understand the influence of the PcBN machining on the material, the grinding process also needs to be assessed via the identification of chip formation mechanisms, which is as well addressed in this work. The main outcome of this study, combining a material analysis and a manufacturing technology point of view, is that there is so far no evidence of any structural instabilities of PcBN under usual processing conditions.

White etching areas (WEA) and white etching cracks (WEC) are frequently linked to premature bearing failure in conventional high carbon bearing steels like 100Cr6 (SAE 52100). In contrast, no WEA/WEC has yet been reported for the high nitrogen bearing steel X30CrMoN15-1 (SAE AMS 5898). Thus, the present study proves for the first time that X30CrMoN15-1 is also susceptible to develop WEA/WEC under rolling contact fatigue (RCF) when pre-charged with hydrogen. RCF tests conducted in parallel without hydrogen pre-charging resulted in RCF damage only, which identifies hydrogen as an active agent for WEA/WEC formation in X30CrMoN15-1. These findings correspond to the fact that hydrogen diffusion during RCF is often considered to cause or accelerate the formation of WEA/WEC. Additionally, it is observed that the M2(C, N) and M23C6 precipitates of the martensitic microstructure of the X30CrMoN15-1 do not entirely decompose during the WEA formation process as observed for M3C precipitates in 100Cr6. In conclusion, the results for X30CrMoN15-1 strongly suggest that the formation of WEA is driven by a hydrogen-activated local severe plastic deformation process, which initiates continuous dynamic recrystallisation, leading to the characteristic nano-ferritic grains observed in WEA. Also, the highly stable and self-regenerating passive chromium-oxide layer of X30CrMoN15-1 mitigates the risk of WEA/WEC failure during typical RCF operation by hindering the formation and adsorption of ionic hydrogen. Hence, this study emphasises the importance of protecting the base material against hydrogen ingress to delay WEA/WEC formation.

Phase characterization with selected area electron diffraction (SAED) represents a significant challenge when the pattern contains a substantial number of diffraction spots arranged in concentric but incomplete rings. This is a common situation when the crystallites are neither large enough to form a single crystal pattern nor sufficiently small and numerous to form continuous Debye-Scherrer rings. In such circumstances, it is often extremely difficult to distinguish between reflections belonging to a specific phase or to identify reflections that originate from secondary phases. To facilitate the process of phase identification for these kinds of multiphase samples, a macro script with the recursive acronym FINDS (FINDS Identifies Non-matrix Diffraction Spots) was developed on the ImageJ/FIJI platform. The program allows the user to mark diffraction spots of known phases by superimposed rings, making it easy to identify and address additional reflections between them. In addition to the full functionality of calculating and plotting the diffraction ring patterns of the known phases in different styles and colors, FINDS also provides tools for locating spot positions and determining the corresponding d-values of the reflections of interest. The effectiveness of this approach and of the developed program in assisting the process of phase identification with SAED patterns of multiphase samples is demonstrated by two representative examples.

Using the well known Rn ratio method, a protocol has been elaborated for determining the lattice direction for the 15 most common cubic zone axis spot patterns. The method makes use of the lengths of the three shortest reciprocal-lattice vectors in each pattern and the angles between them. No prior pattern calibration is required for the method to work, as the Rn ratio method is based entirely on geometric relationships. In the first step the pattern is assigned to one of three possible pattern types according to the angles that are measured between the three reciprocal-lattice vectors. The lattice direction [uvw] and possible Bravais type(s) and Laue indices of the corresponding reflections can then be determined by using lookup tables. In addition to determining the lattice direction, this simple geometric analysis allows one to distinguish between the P, I and F Bravais lattices for spot patterns aligned along [013], [112], [114] and [233]. Moreover, the F lattice can always be uniquely identified from the [011] and [123] patterns.

Cobalt-Rhenium (Co-Re)-based alloys are currently investigated as potential high-temperature materials with melting temperatures beyond those of nickel-based superalloys. Their attraction stems from the binary Co-Re phase diagram, exhibiting complete miscibility between Co and Re, whereby the melting temperature steadily increases with the Re-content. Thus, depending on the Re-content, one can tune the melting temperature between that of pure Co (1495 °C) and that of pure Re (3186 °C). Current investigations focus on Re-contents of about 15 at.%, which makes melting with standard equipment still feasible. In addition to solid solution strengthening due to the mixture of Co- and Re-atoms, particle strengthening by tantalum carbide (TaC) and titanium carbide (TiC) precipitates turned out to be promising in recent studies. Yet, it is currently unclear which of the two particle types is the best choice for high temperature applications nor has the strengthening mechanism associated with the monocarbide (MC)-precipitates been elucidated. To address these issues, we perform compression tests at ambient and elevated temperatures on the particle-free base material containing 15 at.% of rhenium (Re), 5 at.% of chromium (Cr) and cobalt (Co) as balance (Co-15Re-5Cr), as well as on TaC- and TiC-containing variants. Additionally, transmission electron microscopy is used to analyze the shape of the precipitates and their orientation relationship to the matrix. Based on these investigations, we show that TiC and TaC are equally suited for precipitation strengthening of Co-Re-based alloys and identify climb over the elongated particles as a rate controlling particle strengthening mechanism at elevated temperatures. Furthermore, we show that the Re-atoms are remarkably strong obstacles to dislocation motion, which are overcome by thermal activation at elevated temperatures.

It is a common observation that rolling bearings fail due to the formation of white etching areas and white etching cracks (WEA/WEC). Branching crack networks beneath the surface and an altered microstructure known as WEA are characteristics of the failure mode. Therefore, the WEA-related cracks are known as WEC. In order to shed more light on this so far not fully understood phenomenon, the present study focussed on the role of specific oil additives and their influence on the formation of reaction layers and how these possibly affect the WEA/WEC formation. For this purpose, comprehensive tests were conducted on a three-ring-on-roller test rig using two different fully formulated oil lubricants with samples of SAE 52100 bearing steel. A subsequent carried out analysis by wavelength dispersive X-ray spectroscopy (WDX) and transmission electron microscopy (TEM) revealed the differences in the formed additive-derived reaction layers. While a known WEA/WEC-critical oil formulation, containing the two additives zinc dithiophosphate (ZDDP) and overbased calcium sulfonate (OBCaSul), did not result in any significant formation of reaction layers during mixed / boundary lubrication at an oil influx temperature of 95 degrees C, an oil formulation containing barium and phosphorus performed excellent in this respect. This finding is related to the observation that provocation of WEA/WEC failures in our experiment was always unsuccessful when the barium-and phosphorus-containing oil was used. The use of barium phos-phate containing lubricants could therefore be an effective measure to prevent or significantly delay WEA/WEC damage to bearings.

Stabilization of single metal atoms is a persistent challenge in heterogeneous catalysis. Especially supported late transitions metals are prone to undergo agglomeration to nanoparticles under reducing conditions. In this study, nitrogen-rich covalent triazine frameworks (CTFs) are used to immobilize iridium complexes. Upon reduction at 400 degrees C, immobilized Ir(acac)(COD) on CTF does not form nanoparticles but transforms into a highly active Ir single atom catalyst. The resulting catalyst systems outperforms both the immobilized complex and supported nanoparticles in the dehydrogenation of formic acid as probe reaction. This superior performance could be traced back to decisive changes of the coordination geometry positively influencing activity, selectivity and stability. Spectroscopic analysis reveals an increase of electron density on the cationic iridium site by donation from the CTF macroligand after removal of the organic ligand sphere from the Ir(acac)(COD) precursor complex upon reductive treatment. This work demonstrates the ability of nitrogen moieties to stabilize molecular metal species against agglomeration and opens avenues for catalysts design using isolated sites in high-temperature applications under reducing atmosphere.

The thermostabilities of mesoporous γ-Al2O3 samples with similar initial surface areas and average pore radii, but significantly different pore volumes, were studied in detail. The results show that γ-Al2O3 with highest initial pore volume converts to α-Al2O3 at a significantly higher temperature, along with larger residual surface area and pore volumes after aging. These observations are directly related to the morphologies of the individual particles and the resulting aggregate structures, which were studied by automated crystallite orientation mapping (ACOM-TEM). Large particles with well-developed plate-like morphologies preferentially form dense stacks by assembly via the {110} main basal planes (pseudo-cubic lattice). This arrangement favors sintering and the formation of α-Al2O3 at comparatively low temperatures. Aluminas with higher proportions of the lateral {100} and {111} facets tend to form aggregate structures with higher porosities and lower interparticle contact areas, thus explaining their superior thermostabilities. These findings highlight the importance of the aggregate structure for the purposeful development of alumina-supported catalysts.

Wire electrochemical machining (wire ECM) combines the advantages of wire electrical discharge machining (wire EDM) and electrochemical machining (ECM). The advantages of flexible 2.5 dimensional machining without the need for an application-specific fixture are combined with the excellent surface integrity properties of the ECM. These properties make the process particularly suitable for highly critical components, like fir tree slots in turbine discs. Knowledge of the resulting surface integrity in terms of microstructure formation, oxide layers, etc. is essential for such components. Therefore, in this paper modified rim zones are investigated by wire ECM e.g. with energy filtered transmission electron microscopy.