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A novel method has been optimized so that adhesion layers are no longer needed to reliably deposit patterned gold structures on amorphous substrates. Using this technique allows for the fabrication of amorphous oxide templates known as micro-crucibles, which confine a vapor-liquid-solid (VLS) catalyst of nominally pure gold to a specific geometry. Within these confined templates of amorphous materials, faceted silicon crystals have been grown laterally. The novel deposition technique, which enables the nominally pure gold catalyst, involves the undercutting of an initial chromium adhesion layer. Using electron backscatter diffraction it was found that silicon nucleated in these micro-crucibles were 30% single crystals, 45% potentially twinned crystals and 25% polycrystals for the experimental conditions used. Single, potentially twinned, and polycrystals all had an aversion to growth with the {1 0 0} surface parallel to the amorphous substrate. Closer analysis of grain boundaries of potentially twinned and polycrystalline samples revealed that the overwhelming majority of them were of the 60° ∑3 coherent twin boundary type. The large amount of coherent twin boundaries present in the grown, two-dimensional silicon crystals suggest that lateral VLS growth occurs very close to thermodynamic equilibrium. It is suggested that free energy fluctuations during growth or cooling, and impurities were the causes for this twinning. [ABSTRACT FROM AUTHOR]

Electron beam damage in electron microscopes is becoming more and more problematic in material research with the increasing demand of characterization of new beam sensitive material such as Li based compounds used in lithium-ion batteries. To avoid radiolysis damage, it has become common practice to use Cryo-EM, however, knock-on damage can still occur in conventional TEM/STEM with a high-accelerating voltage (200-300 keV). In this work, electron energy loss spectroscopy with an accelerating voltage of 30,20 and 10 keV was explored with h-BN, TiB 2 and TiN compounds. All Ti L 2,3, N K and B K edges were successfully observed with an accelerating voltage as low as 10 keV. An accurate elemental quantification for all three samples was obtained using a multi-linear least square (MLLS) procedure which gives at most a 5 % of standard deviation which is well within the error of the computation of the inelastic partial-cross section used for the quantification. These results show the great potential of using low-voltage EELS which is another step towards a knock-on damage free analysis., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Raynald Gauvin reports financial support was provided by Natural Sciences and Engineering Research Council of Canada. Raynald Gauvin reports financial support was provided by Hydro-Québec. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

To fulfill power and energy demands, lithium-ion battery (LIB) is being considered as a promising energy storage device. For the development of LIBs, high-resolution electron microscopy characterization of battery materials is crucial. During this characterization, the interaction of beam-electrons with Li-containing materials causes damage through several processes, especially knock-on damage. In this study, we investigated this damage by determining the probability of knock-on damage and performing Monte Carlo simulation. For this objective, the threshold displacement energies (TDEs) were computed using sudden approximation technique for three sets of materials, including pure elements, LiX (X = F, Cl, Br), and Li 2 MSiO 4 (M = Fe, Co, Mn). By including the Climbing-Image Nudge Elastic Band (CI-NEB) method into the sudden approximation approach, it was found that the accuracy of the predicted TDEs could be improved. Results also indicated that at moderate electron energies, the knock-on damage for Li in both its elemental and compound forms maximized. In addition, it was shown that the TDE should be the principal parameter for assessing the Li sensitivity to knock-on damage across similar structures. Nonetheless, other parameters, including cross-section, density, weight fraction, atomic weight, and atomic number, were found to impact the knock-on damage., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Raynald Gauvin reports financial support was provided by Natural Sciences and Engineering Research Council of Canada. Raynald Gauvin reports financial support was provided by Hydro-Québec., (Copyright © 2023. Published by Elsevier B.V.)

This study introduces a universal equation to calculate the geometrical correction factor (G) as the fourth factor in the conventional ZAF method for quantifying spherical particles (specifically, NIST-K411 glass microspheres mounted on bulk carbon substrate). Note that the fluorescence correction factor (F) is not considered in this study. Our findings demonstrate that the G factor, as a function of the particle diameter (D) and the range of emitted X-rays in a bulk sample (Xe), provides the best model. Xe depends on the chemical composition and accelerating voltage. We observed excellent agreement between the G factor predicted by our model and experimental data obtained from NIST-K411 standard particles. Our results show that when Xe is greater than D, the G factor decays exponentially, independent of the incident electron energy, X-ray lines, and chemical composition of the particles. We also found that when DXe > 1, the particle behaves as a bulk sample, and G = 1. Notably, our data indicate that the G factor depends only on DXe, not on the chemical composition or beam energy., Competing Interests: Conflict of Interest The authors declare that they have no competing interest., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Microscopy Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

A novel approach, termed line-rotated remapping (LRR), for high resolution electron backscatter diffraction is proposed to remap patterns with large rotation. In LRR, the displacements during the first-pass cross-correlation is modified to a function of the corresponding Kikuchi lines and the points on the reference pattern. Then, the finite rotation matrix to remap the test pattern to a similar orientation of the reference pattern is determined using the parameters of the Kikuchi lines. We apply LRR to simulated Si patterns with random orientations, and obtain measurement errors below ∼1.0 × 10 -3 for lattice rotations up to ∼26°. The maximum angle that may be remapped by LRR decreases with the distance between the specimen and the screen, which in turn reduces the number of matched Kikuchi lines. We also employ LRR in experiments to quantitatively characterize rotations and elastic strains of a Ni single crystal subject to nanoindentation and tension measurements. Although more experimental data on pattern center and image contrast are required to properly assess the performance of LRR, our method is a promising technique to improve strain measurements in the presence of large rotations., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

Generating quantitative phase maps is unvaluable to access the phase distribution in a material. X-ray hyperspectral mapping using an energy dispersive spectrometer (EDS) attached to a scanning electron microscope (SEM) is the most practical way to collect these data, mainly due to its relatively ease of operation and availability around the world. In this work, we demonstrate an innovative technique to produce high-quality phase maps based on the correlation between each hyperspectral image pixel spectrum and a set of standards spectra. The standards spectra can be obtained experimentally from bulk specimens of known materials but also via analytical computations. The method is not only robust against electron beam current and spectrometer instabilities but also to statistical noise in the standards as well as in the hyperspectral image spectra. Equally, the method is reliable to produce phase distribution maps at low operating voltage where SEM-EDS quantitative x-ray microscopy is limited by many factors like peak overlapping, continuous background approximations and produces inaccurate phase maps. The results presented in this study will certainly open a new path to produce useful x-ray quantitative data and potentially break the locks of conventional x-ray microanalysis using EDS., (Copyright © 2022. Published by Elsevier B.V.)

In the past few decades, nanostructured carbons (NCs) have been investigated for their interesting properties, which are attractive for a wide range of applications in electronic devices, energy systems, sensors, and support materials. One approach to improving the properties of NCs is to dope them with various heteroatoms. This work describes the synthesis and study of sulfur-added carbon nanohorns (S-CNH). Synthesis of S-CNH was carried out by modified chemical vapor deposition (m-CVD) using toluene and thiophene as carbon and sulfur sources, respectively. Some parameters such as the temperature of synthesis and carrier gas flow rates were modified to determine their effect on the properties of S-CNH. High-resolution scanning and transmission electron microscopy analysis showed the presence of hollow horn-type carbon nanostructures with lengths between 1 to 3 µm and, diameters that are in the range of 50 to 200 nm. Two types of carbon layers were observed, with rough outer layers and smooth inner layers. The surface textural properties are attributed to the defects induced by the sulfur intercalated into the lattice or bonded with the carbon. The XRD patterns and X-ray microanalysis studies show that iron serves as the seed for carbon nanohorn growth and iron sulfide is formed during synthesis.

Photocatalysts able to trigger the production of singlet oxygen species are the topic of intense research efforts in organic synthesis. Yet, challenges still exist in improving their activity and optimizing their use. Herein, we exploited the benefits of plasmonic nanoparticles to boost the activity of such photocatalysts via an antenna effect in the visible range. We synthesized silica-coated silver nanoparticles (Ag@SiO 2 NPs), with silica shells which thicknesses ranged from 7 to 45 nm. We showed that they served as plasmonically active supports for tris(bipyridine)ruthenium(II), [Ru(bpy) 3 ] 2+ , and demonstrated an enhanced catalytic activity under white light-emitting diode (LED) irradiation for citronellol oxidation, a key step in the commercial production of rose oxide fragrance. A maximum enhancement of the plasmon-mediated reactivity of approximately 3-fold was observed with a 28 nm silica layer along with a 4-fold enhancement in the emission intensity of the photocatalyst. Using electron energy loss spectroscopy (EELS) and boundary element method simulations, we mapped the decay of the plasmonic signal around the Ag core and provided a rationale for the observed catalytic enhancement. This work provides a systematic analysis of the promising properties of plasmonic NPs used as catalysis-enhancing supports for common homogeneous photocatalysts and a framework for the successful design of such systems in the context of organic transformations.

The microstructures of quenched and tempered steels have been traditionally explored by transmission electron microscopy (TEM) rather than scanning electron microscopy (SEM) since TEM offers the high resolution necessary to image the structural details that control the mechanical properties. However, scanning electron microscopes, apart from providing larger area coverage, are commonly available and cheaper to purchase and operate compared to TEM and have evolved considerably in terms of resolution. This work presents detailed comparison of the microstructure characterization of quenched and tempered high-strength steels with TEM and SEM electron channeling contrast techniques. For both techniques, similar conclusions were made in terms of large-scale distribution of martensite lath and plates and nanoscale observation of nanotwins and dislocation structures. These observations were completed with electron backscatter diffraction to assess the martensite size distribution and the retained austenite area fraction. Precipitation was characterized using secondary imaging in the SEM, and a deep learning method was used for image segmentation. In this way, carbide size, shape, and distribution were quantitatively measured down to a few nanometers and compared well with the TEM-based measurements. These encouraging results are intended to help the material science community develop characterization techniques at lower cost and higher statistical significance., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2021 Nicolas Brodusch et al.)

Electron tomography has been widely applied to three-dimensional (3D) morphology characterization and chemical analysis at the nanoscale. A HAADF-EDS bimodal tomographic (HEBT) reconstruction technique has been developed to extract high resolution element-specific information. However, the reconstructed elemental maps cannot be directly converted to quantitative compositional information. In this work, we propose a quantification approach for obtaining elemental weight fraction maps from the HEBT reconstruction technique using the physical parameters extracted from a Monte Carlo code, MC X-ray. A similar quantification approach is proposed for the EDS-STEM tomographic reconstruction. The performance of the two quantitative reconstruction methods, using the simultaneous iterative reconstruction technique, are evaluated and compared for a simulated dataset of a two-dimensional phantom sample. The effects of the reconstruction parameters including the number of iterations and the weight of the HAADF signal are discussed. Finally, the two approaches are applied to an experimental dataset to show the 3D structure and quantitative elemental maps of a particle of flux melted metal-organic framework glass., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Current quantitative X-ray microanalysis methods are only available for homogeneous materials. This paper presents a newly developed inverse modeling algorithm to determine both the structure and composition of two-dimensional (2D) heterogeneous materials from a series of X-ray intensity measurements under different beam energies and beam positions. It utilizes an iterative process of forward modeling to determine the optimal specimen to minimize the relative differences between the simulated and experimental characteristic X-ray intensities. The Monte Carlo method is used for the forward modeling to predict the X-ray radiation for a given specimen and experimental setup. Several examples of applications are presented for different types of samples with one-dimensional (1D) and 2D structures, in which the simulated X-ray intensities from phantom samples are used as input. Most of the results obtained from our algorithm agree well with the phantom samples. Some discrepancies are found for the voxels located at deeper depths of the 2D samples. And the discrepancies may be attributed to errors from the Monte Carlo simulations and from the variation of the X-ray range with beam energy. As a proof-of-concept work, this paper confirms the feasibility of our inverse modeling algorithm applied to 2D heterogeneous materials., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A method of calculating the magnitude of the core hole screening of lithium materials is implemented for the simulation of Energy Loss Near Edge Structure (ELNES). ELNES is calculated for a range of lithium materials resulting in improved agreement between calculation and experiment. The technique uses linear response theory to relate the electron density to the core hole shielding contribution from the valence electrons in a crystal. This contribution is then implemented via a non-integer core hole in final state rule calculations., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this study, the effect of Scanning Electron Microscopy (SEM) parameters such as magnification ( M ), accelerating voltage ( V ), and working distance (WD) on the 3D digital reconstruction technique, as the first step of the quantitative characterization of fracture surfaces with SEM, was investigated. The 2D images were taken via a 4-Quadrant Backscattered Electron (4Q-BSE) detector. In this study, spherical particles of Ti-6Al-4V (15-45  μ m) deposited on the silicon substrate were used. It was observed that the working distance has a significant influence on the 3D digital rebuilding method via SEM images. The results showed that the best range of the working distance for our system is 9 to 10 mm. It was shown that by increasing the magnification to 1000x, the 3D digital reconstruction results improved. However, there was no significant improvement by increasing the magnification beyond 1000x. In addition, results demonstrated that the lower the accelerating voltage, the higher the precision of the 3D reconstruction technique, as long as there are clean backscattered signals. The optimal condition was achieved when magnification, accelerating voltage, and working distance were chosen as 1000x, 3 kV, and 9 mm, respectively., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2020 Seyed Mahmoud Bayazid et al.)

A serious limitation in the use of energy dispersive spectrometers (EDS) for materials characterization arises from the fact that these x-ray detectors provide a poor energy resolution compared to other x-ray techniques. This is mainly due to the broadening function generated by the electronics of the detector. However, new windowless detectors are now capable of resolving low energy peaks like Li Kα with modified electronics and show a system peak full width at half maximum (FWHM) of around 30 eV. In this paper, we investigated how the Richardson-Lucy algorithm can be used to remove, or at least attenuate, the contribution of the broadening function to experimental spectra. This method proved to be efficient in improving the energy resolution at any energy in the EDS spectrum. The resulting system peak FWHM was reduced to as low as 7-8 eV and the separation of low energy x-ray peaks were demonstrated in the low energy range of the spectra. The method was also efficient in reducing the peak broadening at higher energies (Cu Kα) and the broadening function of the detector could be experimentally determined to provide higher accuracy in predicting peak broadening. Although some critical artefacts were noted on the restored spectra, like energy shifts and intensity variations, the method explored in this work is worth to be considered for further quantification tests., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019. Published by Elsevier B.V.)

A commercial electron energy-loss spectrometer (EELS) attached to a high-resolution cold-field emission scanning electron microscope in transmission mode (STEM) is evaluated and its potential for characterizing materials science thin specimens at low accelerating voltage is reviewed. Despite the increased beam radiation damage at SEM voltages on sensitive compounds, we describe some potential applications which benefit from lowering the primary electrons voltage on less-sensitive specimens. We report bandgap measurements on several dielectrics which were facilitated by the lack of Cherenkov radiation losses at 30 kV. The possibility of volume plasmon imaging to probe local composition changes in complex materials was demonstrated using energy-filtered STEM, either via spectrum imaging or elemental mapping using the "three-windows" method. As plasmonic materials are increasing used for energy, electronics or biomedical applications, the ability of reliably evaluate their properties at low accelerating voltage in a SEM is very appealing and is demonstrated. The energy resolution of the spectrometer, taken as the full width at half maximum of the zero-loss peak, was routinely measured at around 0.55 eV and it is demonstrated that t/λ ratios up to 1.5 allowed practical EEL spectroscopy at 30 kV., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Hollow mesoporous silica capsules (HMSC) are potential drug transport vehicles due to their biocompatibility, high loading capacity and sufficient stability in biological milieu. Herein, we report the synthesis of ellipsoid-shaped HMSC (aspect ratio ∼2) performed using hematite particles as solid templates that were coated with a conformal silica shell through cross-condensation reactions. For obtaining hollow silica capsules, the iron oxide core was removed by acidic leaching. Gas sorption studies on HMSC revealed mesoscopic pores (main pore width ∼38 Å) and a high surface area of 308.8 m 2 g -1 . Cell uptake of dye-labeled HMSC was confirmed by incubating them with human cervical cancer (HeLa) cells and analyzing the internalization through confocal microscopy. The amphiphilic nature of HMSC for drug delivery applications was tested by loading antibiotic (ciprofloxacin) and anticancer (curcumin) compounds as model drugs for hydrophilic and hydrophobic therapeutics, respectively. The versatility of HMSC in transporting hydrophilic as well as hydrophobic drugs and a pH dependent drug release over several days under physiological conditions was demonstrated in both cases by UV-vis spectroscopy. Ciprofloxacin-loaded HMSC were additionally evaluated towards Gram negative ( E. coli ) bacteria and demonstrated their efficacy even at low concentrations (10 μg ml -1 ) in inhibiting complete bacterial growth over 18 hours., Competing Interests: The authors declare no conflicts of interest., (This journal is © The Royal Society of Chemistry.)

A number of techniques for the characterization of rare earth minerals (REM) have been developed and are widely applied in the mining industry. However, most of them are limited to a global analysis due to their low spatial resolution. In this work, phase map analyses were performed on REM with an annular silicon drift detector (aSDD) attached to a field emission scanning electron microscope. The optimal conditions for the aSDD were explored, and the high-resolution phase maps generated at a low accelerating voltage identify phases at the micron scale. In comparisons between an annular and a conventional SDD, the aSDD performed at optimized conditions, making the phase map a practical solution for choosing an appropriate grinding size, judging the efficiency of different separation processes, and optimizing a REM beneficiation flowsheet.

Characterising the impact of lithium additions in the precipitation sequence in Al-Li-Cu alloys is important to control the strengthening of the final material. Since now, transmission electron microscopy (TEM) at high beam voltage has been the technique of choice to monitor the size and spatial distribution of δ' precipitates (Al 3 Li). Here we report on the imaging of the δ' phase in such alloys using backscattered electrons (BSE) and low accelerating voltage in a high-resolution field-emission scanning electron microscope. By applying low-energy Ar + ion milling to the surface after mechanical polishing (MP), the MP-induced corroded layers were efficiently removed and permitted the δ's to be visible with a limited impact on the observed microstructure. The resulting BSE contrast between the δ's and the Al matrix was compared with that obtained using Monte Carlo modelling. The artefacts possibly resulting from the sample preparation procedure were reviewed and discussed and permitted to confirm that these precipitates were effectively the metastable δ's. The method described in this report necessitates less intensive sample preparation than that required for TEM and provides a much larger field of view and an easily interpretable contrast compared to the transmission techniques., (© 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.)

Electron channelling is known to affect the x-ray production when an accelerated electron beam is applied to a crystalline material and is highly dependent on the local crystal orientation. This effect, unless very long counting time are used, is barely noticeable on x-ray energy spectra recorded with conventional silicon drift detectors (SDD) located at a small elevation angle. However, the very high count rates provided by the new commercially available annular SDDs permit now to observe this effect routinely and may, in some circumstances, hide the true elemental x-ray variations due to the local true specimen composition. To circumvent this issue, the recently developed f-ratio method was applied to display qualitatively the true net intensity x-ray variations in a thin specimen of a Ti-6Al-4V alloy in a scanning electron microscope in transmission mode. The diffraction contrast observed in the x-ray images was successfully cancelled through the use of f-ratios and the true composition variations at the grain boundaries could be observed in relation to the dislocation alignment prior to the β-phase nucleation. The qualitative effectiveness in removing channelling effects demonstrated in this work makes the f-ratio, in its quantitative form, a possible alternative to the ZAF method in channelling conditions., (© 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.)

Characterization of the topmost surface of biomaterials is crucial to understanding their properties and interactions with the local environment. In this study, the oxide layer microstructure of plasma-modified 316L stainless steel (SS316L) samples was analyzed by a combination of electron backscatter diffraction and electron channeling contrast imaging using low-energy incident electrons. Both techniques allowed clear identification of a nano-thick amorphous oxide layer, on top of the polycrystalline substrate, for the plasma-modified samples. A methodology was developed using Monte Carlo simulations combined with the experimental results to estimate thickness of the amorphous layer for different surface conditions. X-ray photoelectron spectroscopy depth profiles were used to validate these estimations.

Cold spray is a thermo-mechanical process where the velocity of the sprayed particles affects the deformation, bonding, and mechanical properties of the deposited material, in the form of splats or coatings. At high strain rates, the impact stresses are converted into heat, a phenomenon known as adiabatic shear, which leads to grain re-crystallization. Grain re-crystallization and growth are shown to have a direct impact on the mechanical properties of the cold-sprayed material. The present study ties the microstructural features within the cold-sprayed Ti splats and the substrate to the bonding mechanism and mechanical properties. High-resolution electron channeling contrast imaging, electron backscatter diffraction mapping, and nanoindentation were used to correlate the microstructure to the mechanical properties distribution within the titanium cold-spray splats. The formation of nanograins was observed at the titanium splat/substrate interface and contributed to metallurgical bonding. An increase in grain re-crystallization within the splat and substrate materials was observed with pre-heating of the substrate. In the substrate material, the predominant mechanism of deformation was twinning. A good relationship was found between the hardness and distribution of the twins within the substrate and the size distribution of the re-crystallized grains within the splats.

Due to its very low hardness and atomic number, pure lithium cannot be prepared by conventional methods prior to scanning electron microscopy analysis. Here, we report on the characterization of pure lithium metallic sheets used as base electrodes in the lithium-ion battery technology using electron backscatter diffraction (EBSD) and X-ray microanalysis using energy dispersive spectroscopy (EDS) after the sheet surface was polished by broad argon ion milling (IM). No grinding and polishing were necessary to achieve the sufficiently damage free necessary for surface analysis. Based on EDS results the impurities could be characterized and EBSD revealed the microsctructure and microtexture of this material with accuracy. The beam damage and oxidation/hydration resulting from the intensive use of IM and the transfer of the sample into the microscope chamber was estimated to be <50 nm. Despite the fact that the IM process generates an increase of temperature at the specimen surface, it was assumed that the milling parameters were sufficient to minimize the heating effect on the surface temperature. However, a cryo-stage should be used if available during milling to guaranty a heating artefact free surface after the milling process., (© 2014 Wiley Periodicals, Inc.)

Dark-field (DF) images were acquired in the scanning electron microscope with an offline procedure based on electron backscatter diffraction (EBSD) patterns (EBSPs). These EBSD-DF images were generated by selecting a particular reflection on the electron backscatter diffraction pattern and by reporting the intensity of one or several pixels around this point at each pixel of the EBSD-DF image. Unlike previous studies, the diffraction information of the sample is the basis of the final image contrast with a pixel scale resolution at the EBSP providing DF imaging in the scanning electron microscope. The offline facility of this technique permits the selection of any diffraction condition available in the diffraction pattern and displaying the corresponding image. The high number of diffraction-based images available allows a better monitoring of deformation structures compared to electron channeling contrast imaging (ECCI) which is generally limited to a few images of the same area. This technique was applied to steel and iron specimens and showed its high capability in describing more rigorously the deformation structures around micro-hardness indents. Due to the offline relation between the reference EBSP and the EBSD-DF images, this new technique will undoubtedly greatly improve our knowledge of deformation mechanism and help to improve our understanding of the ECCI contrast mechanisms., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The electron channeling contrast imaging technique was used to investigate the microstructure of copper coatings fabricated by cold gas dynamic spray. The high velocity impact characteristics for cold spray led to the formation of many substructures, such as high density dislocation walls, dislocation cells, deformation twins, and ultrafine equiaxed subgrains/grains. A schematic model is proposed to explain structure refinement of Cu during cold spray, where an emphasis is placed on the role of dislocation configurations and twinning.