High capacity alloy-type materials are attractive anodes for potassium-ion batteries yet their practical use is hampered by extreme volumetric expansion that causes mechanical instability and rapid capacity fading. Here we show that the electrolyte formulation decisively governs both the electrochemical performance and structural integrity of a high-capacity Sb/graphite composite anode (70:30 wt.%). A localized high-concentration electrolyte (LHCE) comprising KFSI, glyme solvents, and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether as diluent delivers markedly improved durability, sustaining over 300 cycles with 400 mAh g-1 (1.5 mAh cm-2), whereas a conventional carbonate-based electrolyte (CBE) exhibits rapid degradation. Operando Raman spectroscopy, operando energy-dispersive X-ray diffraction, operando electrochemical dilatometry, and ex situ XPS and TEM reveal that the benefit arises from a two-dimensional electrolyte effect on both surface and bulk electrode behavior. The CBE promotes crystalline multiphase K-Sb alloying together with pronounced graphite participation and forms a thick, organic-rich SEI, leading to large, poorly reversible swelling and mechanical damage. In contrast, the LHCE favors predominantly amorphous KxSb formation, suppresses deep K+ intercalation into graphite, and forms a thin inorganic, KF-rich interphase that mitigates internal strain. These insights link solvation, interphase chemistry, and chemo-mechanics, guiding electrolyte design for stable alloy anodes.

Angle- and energy-dispersive diffraction are applied to investigate the influence of the X-ray beam diameter on the results of residual stress analysis on a sample with an inhomogeneous surface topography. For sin 2 ψ measurements on parts of the surface featuring a cylindrical topography, modifications of the fundamental equation of X-ray stress analysis are proposed to correct the experimentally determined residual stresses for the rotational effect caused by the different orientation of the local principal stress coordinate system within the irradiated part of the sample. It is shown that the hoop and longitudinal stress components require different treatments in this respect. For the hoop stress component a correction factor is proposed which considers the variation in the illuminated surface area during the ψ tilt of the sample. Correction of the longitudinal stress component requires knowledge of the hoop stress component, which affects the slope of the sin 2 ψ regression line and thus partially acts as a normal stress component. For cases in which ψ tilting is not possible for geometric reasons, the applicability of the transverse contraction method is discussed. Experimental verification is carried out on a ferritic steel sample into which grooves of the same diameter were milled to different depths, resulting in different central angles.

A scattering geometry for depth-resolved energy-dispersive X-ray stress analysis on polycrystalline materials is introduced. Via simultaneous data acquisition during a sin2 ψ measurement using two detectors arranged in the horizontal diffraction plane, it aims to extend the accessible information depth to the free surface as well as deeper material zones. While data acquisition with the first detector takes place in a symmetrical configuration with regard to the incident and exit angles, αi and αe, respectively, the second detector runs in an asymmetrical mode, defined by αi < αe. Therefore, the scattering vectors assigned to the two diffraction geometries run in different tilt planes during a χ scan of the sample performed in the Eulerian cradle. Treatment of the data recorded in the asymmetric diffraction mode requires modifications of the fundamental equation of X-ray stress analysis, which are discussed using the example of measurements performed on a unidirectionally ground ferritic steel sample.

Constrained thermal expansion and contraction during welding cause a compression-tension cycle and plastic deformation in the heat-affected zone, leading to work hardening. The nature of this hardening effect—isotropic or kinematic—determines the final local yield stress and thus affects the residual stress state. Therefore, mechanical hardening must be modeled correctly in welding simulations for accurately predicting welding residual stresses. Previous studies, relying on comparisons with experimental ex situ results, led to different recommendations regarding the choice of the hardening model and thus require clarification. In this work, the stress evolution in the heat-affected zone of a tungsten inert gas weld is studied in situ using energy-dispersive x-ray diffraction and a novel method of stress analysis based on crystallite anisotropy. Additionally, microstructural information is gathered through line profile analysis. Results are shown for both austenitic and ferritic high-alloy steels and compared to ex-situ results including a validation of the new method of stress analysis. Finally, conclusions on the nature of work hardening are drawn.

The influence of various combinations of residual stress, composition and grain interaction gradients in polycrystalline materials with cubic symmetry on energy-dispersive X-ray stress analysis is theoretically investigated. For the evaluation of the simulated sin2ψ distributions, two different strategies are compared with regard to their suitability for separating the individual gradients. It is shown that the separation of depth gradients of the strain-free lattice parameter a 0(z) from residual stress gradients σ(z) is only possible if the data analysis is carried out in section planes parallel to the surface. The impact of a surface layer z* that is characterized by a direction-dependent grain interaction model in contrast to the volume of the material is quantified by comparing a ferritic and an austenitic steel, which feature different elastic anisotropy. It is shown to be of minor influence on the resulting residual stress depth profiles if the data evaluation is restricted to reflections hkl with orientation factors Γ hkl close to the model-independent orientation Γ*. Finally, a method is proposed that allows the thickness of the anisotropic surface layer z* to be estimated on the basis of an optimization procedure.

Two data evaluation concepts for X-ray stress analysis based on energy-dispersive diffraction on polycrystalline materials with cubic crystal structure, almost random crystallographic texture and strong single-crystal elastic anisotropy are subjected to comparative assessment. The aim is the study of the residual stress state in hard-to-reach measurement points, for which the sin 2 ψ method is not applicable due to beam shadowing at larger sample tilting. This makes the approaches attractive for stress analysis in engineering parts with complex shapes, for example. Both approaches are based on the assumption of a biaxial stress state within the irradiated sample volume. They exploit in different ways the elastic anisotropy of individual crystallites acting at the microscopic scale and the anisotropy imposed on the material by the near-surface stress state at the macroscopic scale. They therefore complement each other, in terms of both their preconditions and their results. The first approach is based on the evaluation of strain differences, which makes it less sensitive to variations in the strain-free lattice parameter a 0 . Since it assumes a homogeneous stress state within the irradiated sample volume, it provides an average value of the in-plane stresses. The second approach exploits the sensitivity of the lattice strain to changes in a 0 . Consequently, it assumes a homogeneous chemical composition but provides a stress profile within the information depth. Experimental examples from different fields in materials science, namely shot peening of austenitic steel and in situ stress analysis during welding, are presented to demonstrate the suitability of the proposed methods.

Laser Powder Bed Fusion (PBF-LB/M) additive manufacturing (AM) induces high magnitude residual stress (RS) in structures due to the extremely heterogeneous cooling and heating rates. As the RS can be deleterious to the fatigue resistance of engineering components, great efforts are focused on understanding their generation and evolution after post-process heat treatments. In this study, one of the few of its kind, the RS relaxation induced in an as-built PBF-LB/M AlSi10Mg material by a low-temperature heat treatment (265 °C for 1 h) is studied by means of X-ray and neutron diffraction. Since the specimens are manufactured using a baseplate heated up to 200 °C, low RS are found in the as-built condition. After heat treatment a redistribution of the RS is observed, while their magnitude remains constant. It is proposed that the redistribution is induced by a repartition of stresses between the α-aluminium matrix and the silicon phase, as the morphology of the silicon phase is affected by the heat treatment. A considerable scatter is observed in the neutron diffraction RS profiles, which is principally correlated to the presence (or absence) of pockets of porosity developed at the borders of the chessboard pattern.

Energy-dispersive diffraction under both laboratory and synchrotron conditions was applied to study the hoop stress in the near-surface region of the inner wall of boreholes with a small diameter of 2 mm. By use of different X-ray beam cross sections for the sin 2 ψ measurements, it is demonstrated that the borehole-to-beam-diameter ratio must be considered in the evaluation. A beam cross section which is comparable to the borehole diameter reduces the slope of the d hkl φψ –sin 2 ψ distributions and thus invalidates the result of stress analysis. A quantitative relationship is applied, which allows the results obtained under the above conditions to be scaled so that they reflect the actual residual stress state at the measurement position. Owing to the small diffraction angles, energy-dispersive diffraction proves to be the only suitable experimental technique that allows a nondestructive and depth-resolved analysis of the hoop stress component at the inner surface of boreholes with a large length-to-diameter ratio.

The stress behavior and the associated microstructure evolution of industrial Ti(C,N)/α-Al2O3 coatings subjected to thermal cycling are investigated by in situ energy dispersive synchrotron X-ray diffraction and transmission electron microscopy. Temperature-dependent stresses and changes in microstructural parameters (domain size and microstrain) are analyzed by in situ measurements at different temperatures between 25 and 800 °C, both in the heating up and cooling down step, including several thermal cycles. Transmission electron microscopy is used to evaluate defects before and after the thermal treatment. The introduction of high compressive stresses in α-Al2O3 by top-blasting is connected to a high defect density at the basal planes of the alumina layer. The stress relaxation of the alumina layer at high temperatures is associated with a successive annihilation of defects until a reversible temperature-dependent stress condition is set. Top-blasting does not change the initial microstructure and residual stress of the Ti(C,N) layer. Ti(C,N) shows a cyclic stress behavior associated with the heat treatment and an elastic deformation behavior in the temperature range investigated.

Two evaluation concepts for nondestructive depth-resolved X-ray residual stress analysis in the near-surface region of materials with cubic symmetry and nearly single crystalline structure are introduced by simulated examples. Both concepts are based on the same data acquisition strategy, which consists in the determination of lattice-spacing depth profiles along the 〈 hkl 〉 poles by stepwise sample rotation around the scattering vector. Segmentation of these profiles parallel to the sample surface provides the lattice strain state as a function of depth. The first evaluation concept extends the crystallite group method developed for materials with pronounced crystallographic texture by the feature of depth resolution and can be applied to samples with arbitrary orientation. The second evaluation concept, which adapts the linear regression approach of the sin 2 ψ method for the case of single crystalline materials, is restricted to samples with (001) orientation. The influence of the strain-free lattice parameter a 0 on residual stress analysis using both evaluation concepts is discussed on the basis of explicitly derived relations.

Scandium-alloying of aluminum nitride (AlScN) enhances the piezoelectric properties of the material and increases the performance of piezoelectric microelectromechanical systems (MEMS). However, this enhancement is caused by the destabilization of the wurtzite phase and so far the stability of AlScN thin films has not been sufficiently studied. Stability is especially important for piezoelectric devices because changes to the film microstructure or residual stress can lead to drastic changes in the device behavior. The stability of AlScN is investigated by annealing sputtered films and characterizing the resulting changes. It is found that the wurtzite phase of ${\mathrm{Al}}_{0.7}{\mathrm{Sc}}_{0.3}\mathrm{N}$ is stable at least up to $1000{\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}$ and annealing increases the crystal quality, reaching a maximum at $800{\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}$. When annealed for more than 100 h at $1000{\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}$, argon used in sputtering segregates into the grain boundaries and causes compressive strains and formation of rock-salt phase. Additionally, annealing at $1000{\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}$ for 5 h reduces the average tensile stress by approximately 1 GPa.

Nickel(Ni)/aluminium(Al) hybrid foams are Al base foams coated with Ni by electrodeposition. Hybrid foams offer an enhanced energy absorption capacity. To ensure a good adhering Ni coating, necessary for a shear resistant interface, the influence of a chemical pre-treatment of the base foam was investigated by a combination of an interface morphology analysis by focused ion beam (FIB) tomography and in situ mechanical testing. The critical energy for interfacial decohesion from these microbending fracture tests in the scanning electron microscope (SEM) were contrasted to and the results validated by depth-resolved measurements of the evolving stresses in the Ni coating during three-point bending tests at the energy-dispersive diffraction (EDDI) beamline at the synchrotron BESSY II. Such a multi-method assessment of the interface decohesion resistance with respect to the interface morphology provides a reliable investigation strategy for further improvement of the interface morphology.

A range of heat treatments have been developed for wrought Inconel 718 to obtain desired properties. For additively manufactured Inconel 718, the recently developed standard ASTM F3301 provides guidance for heat treatment of powder bed fusion specimens. Although this standard is based on standards developed for wrought Inconel 718, it does not include direct aging. Since direct aging reduces the number of processing steps, it can result in a post processing cost reduction if the desired properties are obtained. In this study, we characterized the microstructure and tensile behavior of Inconel 718 specimens produced by a laser powder bed fusion process. The specimens were heat treated according to two different routines after stress relieving: a full heat treatment versus a one-step direct aging process. Differences in the resulting texture and grain morphology were observed. The ex-situ stress-strain behavior was broadly similar. However, a slight increase in yield strength was observed for the direct aged specimen. In order to understand this behavior, investigations with in-situ synchrotron energy dispersive X-ray diffraction tensile testing revealed differences in the load partitioning among different crystal directions. Importantly, the elastic anisotropy expressed by the magnitude of the diffraction elastic constants showed a dependency on the microstructures.

EDDIDAT is a MATLAB-based graphical user interface for the convenient and versatile analysis of energy-dispersive diffraction data obtained at laboratory and synchrotron sources. The main focus of EDDIDAT up to now has been on the analysis of residual stresses, but it can also be used to prepare measurement data for subsequent phase analysis or analysis of preferred orientation. The program provides access to the depth-resolved analysis of residual stresses at different levels of approximation. Furthermore, the graphic representation of the results also serves for the consideration of microstructural and texture-related properties. The included material database allows for the quick analysis of the most common materials and is easily extendable. The plots and results produced with EDDIDAT can be exported to graphics and text files. EDDIDAT is designed to analyze diffraction data from various energy-dispersive X-ray sources. Hence it is possible to add new sources and implement the device-specific properties into EDDIDAT. The program is freely available to academic users.

In this work, the stress gradient in mechanically polished tungsten sample was studied using X-ray diffraction methods. To determine in-depth stress evolution in the very shallow subsurface region (up to 10 μ m), special methods based on reflection geometry were applied. The subsurface stresses (depth up to 1 μ m) were measured using the multiple-reflection grazing incidence X-ray diffraction method with classical characteristic X-rays, while the deeper volumes (depth up to 10 μ m) were investigated using energy-dispersive diffraction with white high energy synchrotron beam. Both complementary methods allowed for determining in-depth stress profile and the evolution of stress-free lattice parameter. It was confirmed that the crystals of tungsten are elastically isotropic, which simplifies the stress analysis and makes tungsten a suitable material for testing stress measurement methods. Furthermore, it was found that an important compressive stress of about − 1000 MPa was generated on the surface of the mechanically polished sample, and this stress decreases to zero value at the depth of about 9 μ m. On the other hand, the strain-free lattice parameter does not change significantly in the examined subsurface region.

The foaming behaviour of aluminium alloys processed by the powder compaction technique depends crucially on the exact alloy composition. The AlSi8Mg4 alloy has been in use for a decade now, and it has been claimed that this composition lies in an “island of good foaming”. We investigated the reasons for this by systematically studying alloys around this composition by varying the Mg and Si content by a few percent. We applied in situ X-ray 2D and 3D imaging experiments combined with a quantitative nucleation number and expansion analysis, X-ray tomography of solid foams to assess the pore structure and pore size distribution, and in situ diffraction experiments to quantify the melt fraction at any moment. We found a correlation between melt fraction and expansion height and verified that the “island of good foaming” actually exists, and foams outside a preferred range for the liquid fraction—just above TS and between 40–60%—show a poorer expansion performance than the reference alloy AlSi8Mg4. A very slight increase of Si and decrease of Mg content might further improve this foam.

An experimental technique is described for the collection of time-resolved X-ray diffraction information from a complete commercial battery cell during discharging or charging cycles. The technique uses an 80 x 80 pixel 2D energy-discriminating detector in a pinhole camera geometry which can be used with a polychromatic X-ray source. The concept was proved in a synchrotron X-ray study of commercial alkaline Zn-MnO2 AA size cells. Importantly, no modification of the cell was required. The technique enabled spatial and temporal changes to be observed with a time resolution of 20 min (5 min of data collection with a 15 min wait between scans). Chemical changes in the cell determined from diffraction information were correlated with complementary X-ray tomography scans performed on similar cells from the same batch. The clearest results were for the spatial and temporal changes in the Zn anode. Spatially, there was a sequential transformation of Zn to ZnO in the direction from the separator towards the current collector. Temporally, it was possible to track the transformation of Zn to ZnO during the discharge and follow the corresponding changes in the cathode.

Energy-dispersive Laue diffraction (EDLD) is a tool for the characterization of single-crystalline and polycrystalline materials. Using a two-dimensional energy-dispersive detector, both the angular positions and the diffracting energies of the Laue spots can be analysed without additional information, allowing for fast indexing, determination of the crystal structure and the respective lattice parameters. Running the detector at ≈ 400 Hz, a typical data set (≈ 10 min) taken by the single photon counting mode has a size of ten Gigabytes. Up to now, problems such as data transfer, data storage, data reduction and on time data analysis are drawbacks for wider application of this technique. A fast and effective algorithm for processing of these BIG Data is required to overcome the drawbacks and to allow for quality assessment of the running experiment in real time. This paper presents a GPU based tool for energy-dispersive Laue diffraction (EDLD) experiments, named “EDLD-Tool”, providing the optimization of geometric parameters of the experiment, auto-indexation, online steering, error detection and determination of all crystal parameters considering pnCCD data taken from a single crystal. This tool is exploiting parallel computing technology of the GPU and makes use of many scientific, high performance libraries (i.e. OpenCV, Root-Cern, Eigen and others). As a result, the developed tool allows for data processing in the time frame of few seconds compared to the previous analysis system which requires few hours to process the same amount of data.

Buried wurtzite structures composed by stacking faults of the {111} planes in zinc-blende and {112} planes in chalcopyrite structures can result in barriers for charge carrier transport. A precise understanding of stacking fault annihilation mechanisms is therefore crucial for the development of effective deposition processes. During co-evaporation of Cu(In,Ga)Se-2-a photovoltaic absorber material showing record efficiencies of up to 22.9% for thin film solar cells a reduction of stacking faults occurs at the transition from a Cu-poor to a Cu-rich film composition, parallel to grain growth, which is suggesting that the two phenomena are coupled. Here, we show by in situ synchrotron X-ray diffraction during annealing of Cu-poor CuInSe2 thin films that stacking faults can be strongly reduced through annealing, without passing through a Cu-rich film composition. We simulate the evolution of the X-ray diffraction stacking fault signal with a simple numerical model of grain growth driven by stacking fault energy and grain boundary curvature. The results support the hypothesis that the stacking fault reduction can be explained by grain growth. The model is used to make predictions on annealing times and temperatures required for stacking fault reduction and could be adapted for polycrystalline thin films with similar morphology.

Energy dispersive X-ray Laue diffraction is applied to investigate the deformation behavior of individual grains in a polycrystalline nickel wire under tensile loading. 38 Laue spots are identified in the Laue pattern which originate from 9 separate grains. The simultaneous measurements of the Laue spot's position and energy obtained by using a 2D energy dispersive detector, allows to track the evolution of the 9 grains through multiple stages of deformation. Angular and spectral elongation (streaking) of the Laue spots increases as tensile loading is increased and is attributed to macroscopic texture changed and strain due to defect accumulation. On the single grain level, a correlation between crystallographic orientation and strain is investigated. Moreover, spatially resolved anisotropic deformation within a single grain is measured to increase at the grain boundaries. Comparison of the grain specific responses allow for development of a deformation scenario for the whole specimen. The presented experiment demonstrates an alternative protocol for the investigation of deformation mechanisms in polycrystalline materials.