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The interactions between hydrogen and crystallographic defects are the key to understanding hydrogen induced localized plasticity or damage mechanisms. However, unraveling such interactions based on the resulting mechanical effects alone can be challenging, due to the spectrum of various effects hydrogen can create in a given microstructure. Pre-deformation or post-mortem characterization of hydrogen segregation has similar limitations, as they can only provide snapshots of these complex processes with challenging spatial and temporal scales. To tackle this, we design in situ experiments that combine electron channeling contrast imaging (ECCI), electron backscattered diffraction (EBSD), and desorption spectroscopy, to investigate hydrogen defect interactions, under no external loading. We show that the inhomogeneous hydrogen distribution within microstructures can cause long-range (>200 nm) dislocation rearrangements. Interpretation of these results as manifestations of boundary-segregation induced stress suggests that microstructural characteristics on either side of the boundary should also play an important role. We provide quantitative assessments of these microstructure neighborhood effects and discuss additional contributions from hydrogen-induced changes in stacking fault energy and elastic modulus. • Hydrogen presence can alter defect substructures and local crystal orientation. • Defect activity likely arise from local lattice accommodation of H-induced stresses. • HE-resistant design lies in uniform H-distribution and accommodating textures. [ABSTRACT FROM AUTHOR]

Mollusk shells protect the animals that form and inhabit them. They are composites of minerals and organics, with diverse mesostructures, including nacre, prismatic calcite, crossed‐lamellar aragonite, and foliated calcite. Twins, that is, crystals mirror symmetric with respect to their coherent interface, occurring as formation or deformation twins, are observed in all mollusk shell mesostructures but never within calcite prisms. Here, nanotwins and microwins within single calcite prisms are observed in different shells. Using Polarization‐dependent Imaging Contrast (PIC) mapping with 20–60 nm resolution, twins are observed to be 0.2–3 µm thick layers of differently oriented and colored crystals with respect to the main prism crystal. Multiple twins are interspersed with the prism crystal, parallel to one another, and similarly oriented. When comparing images of calcite prisms and twins obtained by PIC mapping and by Electron Back‐Scattered Diffraction (EBSD), the images correspond precisely. All twins are e‐twin types, with 127° angular distance between c‐axes. E‐twins are the most common deformation twins in geologic calcite, as also observed here in Carrara marble. Location of all twins near the outer surface of all shells and e‐twin type both suggest that twins within calcite prisms in mollusk shells result from deformation twinning. [ABSTRACT FROM AUTHOR]

In this article, the evolution of microstructural characteristics of selectively laser-melted AlSi10Mg alloy subjected to equal channel angular pressing (ECAP) is investigated. The microstructures were analyzed in detail using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission Kikuchi diffraction (TKD), and transmission electron microscopy (TEM). A heterogeneous ultrafine-grained microstructure was produced after one ECAP pass at 100 °C. This microstructure was composed of Al/Si cells and sub-micrometer grains. The grains were refined by conventional dislocation processes; however, evidence of dynamic recrystallization was also documented. Furthermore, it was revealed that the Al/Si cells contribute significantly to grain refinement. EBSD/TKD investigations showed that cell misorientation increased after ECAP processing, resulting in an increased fraction of grains with very low misorientation angles. [ABSTRACT FROM AUTHOR]

Chamid bivalves are marine organisms that live in high-energy environments and are cemented to hard substrates. To avoid shell damage, the organisms form thick, densely ornamented shells. Shell material consists of aragonite, and the ornamentation may be either aragonitic or calcitic. The latter can be developed as scaly spines, rows of blades, or comarginal, radial arched lamellae. We investigated biological crystal morphology and mode of assembly of Chama arcana and Chama gryphoides shells. Structural characteristics were obtained from electron backscatter diffraction (EBSD) measurements, complemented with laser confocal and BSE imaging. We found a wide range of crystal morphologies and sizes, ranging from irregularly shaped calcite and/or aragonite prisms to tiny and thin aragonite laths. We observed four different modes of crystal assembly patterns: 1. strongly interlocked dendritic calcite units forming the ornamentation blades; 2. aragonite laths arranged to lamellae forming the outer shell layer, the layer adjacent to the calcite; 3. aragonite laths arranged into blocks comprising inner shell layers or aragonitic ornamentations; and 4. shell portions consisting of aragonite prisms, structured in size and crystal orientation, at muscle attachment sites. These four different types of crystal arrangements were observed for the shells of the investigated chamid species; however, they had slightly different strengths of structuring and slight variations in crystal organisation. Additionally, we observed unique microstructural features in Chama shells: We report ornamentation crystals resembling idiomorphic calcite and novel, twinned entities found at the changeover between the aragonitic layers. We highlight and discuss these differences and anomalies in this contribution. [ABSTRACT FROM AUTHOR]

Owing to its reflectivity, Copper manufacturing has always been challenging through laser-based additive manufacturing. In this study, we demonstrate additive/bulk manufacturing of copper using high velocity air fuel (HVAF) spray technology, an emerging variant in the thermal spray family. Rapid deposition of millimeter scale copper parts with good mechanical integrity and decent ductility, comparable to that of cold spray, has been shown feasible. The mechanical properties measured along different built directions showed no significance to be considered anisotropic. Electron backscattered diffraction analysis revealed the possibility of developing favorable bimodal grain distribution with a high volume fraction of ultrafine grains (>50%). However, the intersplat porosities and continuous pores were found to be detrimental despite the low overall porosity. HVAF technology demonstrates great potential and appears to be a promising process methodology for bulk/additive manufacturing of metals with a rapid production rate. [ABSTRACT FROM AUTHOR]

This study provides a methodology for exploring the microstructural and mechanical properties of the Haynes®282® alloy produced via the Powder Bed Fusion-Electron Beam (PBF-EB) process. Employing 2D Electron Backscatter Diffraction (EBSD) data, we have successfully generated 3D representations of columnar microstructures using the Representative Volume Element (RVE) method. This methodology allowed for the validation of elastic properties through Crystal Elasticity Finite Element (CEFE) computational homogenization, revealing critical insights into the material behavior. This study highlights the importance of accurately representing the grain morphology and crystallographic texture of the material. Our findings demonstrate that created virtual models can predict directional elastic properties with a high level of accuracy, showing a maximum error of only ~5% compared to the experimental results. This precision underscores the potential of our approach for predictive modeling in Additive Manufacturing (AM), specifically for materials with complex, non-homogeneous microstructures. It can be concluded that the results uncover the intricate link between microstructural features and mechanical properties, underscoring both the challenges encountered and the critical need for the accurate representation of grain data, as well as the significance of achieving a balance in EBSD area selection, including the presence of anomalies in strongly textured microstructures. [ABSTRACT FROM AUTHOR]

Rock textures observed via thin section are skewed from their true 3D nature. This is due to various cut effects—artifacts introduced due to the lower dimensional nature of the thin section relative to the rock. These cut effects can be corrected, and several methods have been developed to invert crystal shape and crystal size, but with each process performed separately and sequentially. With the ongoing adoption of electron backscatter diffraction (EBSD) by petrologists, an additional data stream has now become available: the 3D orientation of 2D grain sections. For EBSD analysis, no stereological corrections are typically applied for interpreting the data. This study tests whether this orientational information is skewed due to a fabric cut effect. We test this by numerically generating synthetic crystal datasets representative of several crystal shapes and population sizes. We find that EBSD orientational data has a fabric cut effect since crystals oriented with long axes perpendicular to the thin section are more likely to be sampled compared to those with long axes oriented parallel to it. This effect must be accounted for to interpret the true 3D fabric accurately. Towards this end, we develop two new tools for working with EBSD-derived fabric: (1) a simple first-order test for determining if a measured fabric exceeds that of the fabric cut effect, and (2) a method of inverting cut fabrics that provides robust error estimations. We demonstrate the applicability and accuracy of these methods using a range of synthetic examples and a natural sample. With these newly developed tools, there is clear potential for a new textural toolkit framework, to further our ability to correct for the various cut effects while also providing accurate uncertainty estimates. [ABSTRACT FROM AUTHOR]

Explaining the crystallography of iron alloys martensite with a {225}γ habit plane remains a challenging task within the phenomenological theory of martensite crystallography. The purpose of this study is to re-examine the martensite formed in a Fe-8Cr-1.1C alloy using EBSD, which has a better angular resolution than the conventional transmission electron diffraction techniques previously used. The results show that the single morphological plates, which hold a near {225}γ habit plane, are bivariant composites made up of two twin-related variants. It is shown that a {113}γ plane is systematically parallel to one of the three common 112 α planes between the two twin-related crystals. This observation suggests that the lattice invariant strain of transformation occurs through a dislocation glide on the {113}γ 〈110〉γ system, rather than through twinning as is commonly accepted. Based on this assumption, the predictions of Bowles and Mackenzie's original theory are in good agreement with the crystallographic features of {225}γ martensite. Unexpectedly, it is the high shear solution of the theory that gives the most accurate experimental predictions. [ABSTRACT FROM AUTHOR]

The automated indexing and orientation determination of backscattered Kikuchi patterns is an essential step in electron backscattered diffraction (EBSD) analysis. Here a new Radon‐transform‐based algorithm is developed within the software package PyEBSDIndex, which features a number of key improvements over what has been traditionally available. The Radon convolutions use derivatives of Gaussian kernels that more closely match EBSD band profiles, which is combined with sub‐pixel localization of the peaks in the Radon transform. Additionally, the weighted quaternion estimator algorithm (QUEST) is leveraged to provide the final estimation of the crystal orientation. The combination of these techniques allows for high‐accuracy indexing and precise orientation determination, with tests on simulated patterns showing mean orientation errors as low as 0.037° and a 95% confidence level of 0.073°. Additional testing of the effect of pattern noise shows that PyEBSDIndex performs similarly to the spherical harmonic transform indexing methods except in the most extreme levels of low pattern quality. A test case of indexing a dual‐phase Ti‐6Al‐4V EBSD map finds that PyEBSDIndex differentiates phases equivalently to the commercial Hough indexing solution, with orientation noise 75% lower than the commercial solution. Finally, it is shown that PyEBSDIndex, by performing the image processing calculations on the GPU, is able to analyze patterns at unprecedented speeds, in some cases at over 45 000 patterns s−1, thereby providing sufficient speed for newer, high‐speed detectors. PyEBSDIndex is open source and available at https://github.com/USNavalResearchLaboratory/PyEBSDIndex. [ABSTRACT FROM AUTHOR]

The effect of weld chemistry (two types of electrodes (E2594 and E2595)) on the microstructure and texture development using electron back scattered diffraction and thermal stability during shielded metal arc welding of alloy 2507 have been studied. Base metal showed alternate bands of austenite (γ) and ferrite (δ) in almost equal fractions. Weldments were mainly comprised of 3 zones, namely base metal zone (BMZ), heat affected zone (HAZ), and weld metal zone (WMZ). After welding, ferritic solidification mode was found with diverse morphologies of austenite viz. grain boundary austenite, Widmanstatten austenite, and intergranular austenite and a decrease in the fraction of austenite in WMZ and HAZ. The texture intensity of δ was observed to be higher than that of γ. This implies a stronger texture for δ (a strong rotated cube texture 001 110 along with minor α-fibre rolling direction , RD / / 110 and γ-fibre normal direction , ND / / 111 ) than γ [Brass, Cu, Goss and S texture components ( 110 112 , 112 111 , 110 001 and 123 634 , respectively)] in the annealed state (BMZ). γ/δ grains showed the Kurdjumov–Sachs (K–S) orientation relationship. Kernel average misorientation (KAM) graphs/maps showed no significant change in BMZ but a substantial decrease in KAM values in δ than γ for both weldments. The peak temperature attained was sufficiently higher than the melting temperature of base/filler metal suggesting the proper melting and diffusion of molten metal throughout the thickness. The size of the melt pool widened for E2594 and was relatively small for E2595. [ABSTRACT FROM AUTHOR]

The Jitang metamorphic complex is key to studying the tectonic evolution of the Northern Lancangjiang zone. Through structural‐lithological mapping, structural analysis and laboratory testing, the composition of the Jitang metamorphic complex was determined. The macro‐ and microstructural analyses of the ductile detachment shear zone (Guoxuepu ductile shear zone, 2–4 km wide) between the metamorphic complex and the overlying sedimentary cap show that the shear sense of the ductile shear zones is top‐to‐the‐southeast. The presence of various deformation features and quartz C‐axis electron backscatter diffraction (EBSD) fabric analysis suggests multiple deformation events occurring at different temperatures. The average stress is 25.68 MPa, with the strain rates (έ) ranging from 9.77×10–14 s–1 to 6.52×10–16 s‐1. The finite strain of the Guoxuepu ductile shear zone indicates an elongated strain pattern. The average kinematic vorticity of the Guoxuepu ductile shear zone is 0.88, implying that the shear zone is dominated by simple shear. The muscovite selected from the protomylonite samples in the Guoxuepu ductile shear zone yields a 40Ar‐39Ar age of 60.09 ± 0.38 Ma. It is suggested that, coeval with the initial Indo–Eurasian collision, the development of strike‐slip faults led to a weak and unstable crust, upwelling of lower crust magma, then induced the detachment of the Jitang metamorphic complex in the Eocene. [ABSTRACT FROM AUTHOR]

Because microstructure plays an important role in the mechanical properties of structural materials, developing the capability to quantify microstructures rapidly is important to enabling high‐throughput screening of structural materials. Electron backscatter diffraction (EBSD) is a common method for studying microstructures and extracting information such as grain size distributions (GSDs), but is not particularly fast and thus could be a bottleneck in high‐throughput systems. One approach to accelerating EBSD is to reduce the number of points that must be scanned. In this work, we describe an iterative method for reducing the number of scan points needed to measure GSDs using incremental low‐discrepancy sampling, including on‐the‐fly grain size calculations and a convergence test for the resulting GSD based on the Kolmogorov–Smirnov test. We demonstrate this method on five real EBSD maps collected from magnesium AZ31B specimens and compare the effectiveness of sampling according to two different low discrepancy sequences, the Sobol and R2 sequences, and random sampling. We find that R2 sampling is able to produce GSDs that are statistically very similar to the GSDs of the full density grids using, on average, only 52% of the total scan points. For EBSD maps that contained monodisperse GSDs and over 1000 grains, R2 sampling only required an average of 39% of the total EBSD points. [ABSTRACT FROM AUTHOR]

A Cu-1Cr-0.1Zr alloy has been subjected to ECAP processing via route Bc and aging at 250-800°C. Electron BackScatter diffraction (EBSD), Transmission Electron Microscopy (TEM) and X-Ray Diffraction Line Profile Analysis (XRDLPA) techniques have been used to unveil some peculiarities of the grain and subgrain structure with a special emphasis on the comparison of the grain size estimated by the three techniques. For the alloy ECAP processed and aged up to 16 passes, the grain size (from EBSD, 0.2 < d < 5 µm), subgrain size (from TEM, d ~ 0.75 µm) and "apparent" average crystallite size (from XRDLPA, d < 0.25 µm) are manifestly different. The results were compared to the published data and analyzed based on the fundamental aspects of these techniques. [ABSTRACT FROM AUTHOR]

Electron backscatter diffraction (EBSD) is an excellent tool for characterizing the crystallographic orientation aspects of the microstructure of polycrystalline material. In some additively manufactured materials, the material may undergo a phase transformation during the forming process. Although EBSD can only characterize the final microstructure, neighbor information from orientation mapping allows the microstructure before the phase transformation to be reconstructed, provided that the parent–child orientation relationship is known. An investigation of the effectiveness of the reconstruction algorithms for capturing the grain size as well as orientation gradients is undertaken with a focus on additively manufactured Ti-alloy. The EBSD results, coupled with reconstruction algorithms, reveal information on the prior grain size as well as the plastic flow of the material. [ABSTRACT FROM AUTHOR]

Metal additive manufacturing is a developing technique with numerous advantages and challenges to overcome. As with all manufacturing techniques, the specific raw materials and processing parameters used have a profound influence on microstructures and the resulting behavior of materials. It is important to understand the relationship between processing and microstructures of Ti to advance knowledge of Ti-alloys in the additive field. In this study, a face-centered cubic (FCC) phase was found in grade 2 commercially pure titanium specimens, additively manufactured with directed energy deposition in an argon atmosphere. Two scanning speeds (500 and 1000 mm/min) and three scanning patterns (cross-hatched and unidirectional patterns) were investigated. Electron backscatter diffraction and energy-dispersive X-ray spectroscopy were used for microstructural and compositional analysis. Inverse pole figure, phase, and kernel average misorientation (KAM) maps were analyzed in this work. Larger amounts of the FCC phase were found in the unidirectional scanning patterns for the slower scanning speed, while the cross-hatched pattern for both scanning speeds showed a lower amount of FCC. Higher KAM averages were present in the faster scanning speed specimens. According to EDS scans, small amounts of nitrogen were uniformly distributed throughout the specimens, leading to the possibility of interstitial content as a contributing factor for development of the observed FCC phase. However, there is no clear relationship between nitrogen and the FCC phase. The formation of this FCC phase could be connected to high densities of crystalline defects from processing, plastic deformation, or the distribution of interstitials in the AM structure. An unexpected Kurdjumow–Sachs-type orientation relationship between the parent beta phase and FCC phase was found, as 110 B C C ∥ 111 F C C , 111 B C C ∥ 110 F C C . [ABSTRACT FROM AUTHOR]

Finite element simulations and forming limit diagram experiments of cupping tests were used to characterize the stamping formability of copper-containing antimicrobial stainless steels, and electron backscatter diffraction (EBSD) technique was used to characterize the microstructure of the samples at different locations of stamping and forming. The experimental results show that circular cracks appear in the raise sidewall area of the sample, and the simulate locations of the cracks are consistent. The EBSD analysis reveals that the closer to the crack position will continuously produce the proliferation of dislocations, so that the small-angle grain boundaries increase significantly, and higher KAM values exist on local grain boundaries or inside a small number of grains. With the change of stamping displacement, part of the austenite phase transforms into martensitic, the slip deformation continues to increase, and the Cube texture transforms into Brass texture. [ABSTRACT FROM AUTHOR]

In the present work, microstructure, texture, and mechanical properties were investigated for the heat-treated two-phase (α + β) titanium alloy samples. Ti-6.5%Al-4.4%V-0.15%Fe alloy samples were heated to three different temperatures (850, 930, and 1066 °C) followed by oil quenching (OQ), air cooling (AC), and furnace cooling (FC), respectively. Primary alpha (αP) and secondary alpha (αS) were dominant in the microstructure, when heat-treated below βT (beta-transus) temperature, i.e., 850 and 930 °C. Widmanstatten α (αWS) and basket-weave α (αBW) were dominant features in the microstructure of the samples heat-treated above the βT, i.e., 1066 °C. Formation of the martensite (α′) was observed in all three cases of the OQ samples. Differences in the volume fraction of the αP and αS were observed in the microstructure due to differences in the heating temperature and cooling rate. Texture developments after heat treatment were measured through the electron back-scatter diffraction (EBSD) technique. Variation in the texture intensity values was observed in the samples heat-treated below the βT which shows the dependence of the texture on the volume fraction of αP and αS. Similarly, formation of the big α colonies causes the changes in the texture when heat-treated above the βT. Grain partitioning of αP and αS in 850 and 930 °C-OQ samples shows a similar type of the texture for both the phases, difference being in the intensity of the texture fibers. Martensite (α′) formation during OQ increased the microhardness, whereas coarsening of grains during FC decreased the microhardness of the samples. There was ~ 23% variation in the modulus of elasticity (E), which depended on the heating temperature and cooling rate. [ABSTRACT FROM AUTHOR]

Microstructural deformation and the age of monazite (Ce) from diatectite granite of the presumably impact Jarva-Varaka structure in the Kola Region (northeastern Fennoscandian Shield) are presented. Biotite diatectite granite forms lenses in the aluminous gneisses of the Kola group hosting the 2.5-Ga-layered Jarva-Varaka Massif (JVM). A sample of biotite granite was collected northeast of the Jarva-Varaka Massif near the earlier described pseudotachylitic breccias. BSE images revealed primary domains in monazite grains with rhythmic euhedral zoning and secondary altered domains. Backscattered electron diffraction maps of monazite grains document the development of deformation twins along {100} and {001} and plastically deformed domains with a maximum misorientation of up to 10°. Newly formed areas of recrystallization (neoblasts) cut the twins and plastically deformed domains. Monazite yielded a U-Pb age of 2706 ± 10 Ma (ID-TIMS method), which defines the crystallization age of the host diatectite granite coeval to the 2.76–2.70 Ga metamorphism of the Kola gneisses. A similar age of 2734 ± 139 Ma (ThO2*–PbO isochron) was obtained for primary monazite domains by the chemical U-Th-total Pb isochron method (CHIME). Domains altered under late hydrothermal processes yield CHIME ages of 1796–1723 Ma. Monazite neoblastic domains are close to primary domains in chemical composition and yielded CHIME ages of 2550–2519 Ma, reflecting probably an influence of the JVM formation. The data obtained are insufficient to confirm the impact origin of the Jarva-Varaka structure, which requires further investigation. [ABSTRACT FROM AUTHOR]

Electron backscatter diffraction (EBSD) investigation of strain mainly uses polycrystalline samples to study fabric development. We extend the use of EBSD for the analysis of large single mineral grains by measuring the apparent surficial subdomain boundary density per unit area, reported here as unit segment length (USL). We apply this USL technique to examine and quantify the plastic deformation recorded by naturally shocked olivine in the low to moderately shocked ureilite meteorite Northwest Africa 2221 and the highly shocked martian dunitic cumulate meteorite Northwest Africa 2737, by assessing the types of subdomain boundaries and the increase of subdomain misorientation with increasing shock metamorphism. We further compare USL results for the shocked olivine in the meteorites with those for the terrestrial deformation of Hawaiian olivine. USL of olivine increases with shock level, and USL from shocked olivine is significantly greater than that of terrestrially deformed olivine. USL is a promising tool for the quantification of plastic deformation in large single crystals from shock as well as terrestrial deformation. The results derived from USL measurements along with local EBSD maps are complementary with quantitative 2D X-ray difraction analysis of crystal deformation and disruption, leading to a more comprehensive understanding of characteristic shock deformation recorded by large single crystals. [ABSTRACT FROM AUTHOR]

The development of automated segmentation and quantitative characterization of microtextured regions (MTRs) from the complex heterogeneous microstructures is urgently needed, since MTRs have been proven to be the critical issue that dominates the dwell-fatigue performance of aerospace components. In addition, MTRs in Ti alloys have similarities to microstructures encountered in other materials, including minerals and biomaterials. Meanwhile, machine learning (ML) offers new opportunities. This paper addresses segmentation and quantitative characterization of MTRs, where an ML approach, the Gaussian mixture models (GMMs) coupled with density-based spatial clustering of applications with noise (DBSCAN) clustering algorithms, was employed in order to process the orientation data acquired via EBSD in the Matlab environment. Pixels with orientation information acquired through electron backscatter diffraction (EBSD) are divided and colored into several "classes" (MTRs) within the defined c-axis misorientations (i.e., 25°, 20°, 15°, 10°, and 5°), the precision and efficacy of which are verified by the morphology and pole figure of the segmented MTR. An appropriate range of c-axis misorientations for MTR segmentation was derived, i.e., 15~20°. The contribution of this innovative technique is compared with previous studies. At the same time, the MTRs were statistically characterized in the global region. [ABSTRACT FROM AUTHOR]

In the present work, the effect of post weld heat treatment (PWHT) on the microstructure and micro-texture evolution in 316L austenitic stainless steel (ASS)/2205 duplex stainless steel dissimilar weldments were studied. Weldments were subjected to PWHT at 950 and 1100 °C for 1 h followed by water quenching. PWHT changed the γ (austenite)/δ (ferrite) ratio, average grain size, and grains boundaries (GBs) fraction in the different zones of the weldments. Grain boundary austenite (γGB), Widmanstatten austenite (γWS), and intragranular austenite (γIG) were observed in the heat affected zone (HAZ) on 2205 side and weld zone (WZ). The HAZ on 2205 side showed significant changes in microstructure after PWHT, whereas HAZ on 316L side did not show any significant changes. PWHT at 950 °C showed lower fraction (35%) of δ-phase, whereas PWHT at 1100 °C had a higher δ-phase fraction (53%) in the HAZ on 2205 side. Kurdjumov–Sachs (KS) orientation relationships (ORs) were observed between γ and δ phases in the as-welded and PHWT specimens. Higher fraction of γ/δ grains in HAZ on 2205 side followed the KS ORs for 1100 °C PWHT than as-welded specimen. γ in the as-welded condition (in 2205 BM) showed strong Brass and S components and weak Copper and Cube components. Texture evolution of δ phase in 2205 BM was the dominant Rotated Cube and weak ND//<111> fiber. PWHT causes change in the texture intensity for both γ and δ phase. A decrease in the microhardness values was observed for the PWHT specimens due to the coarsening of the microstructure. [ABSTRACT FROM AUTHOR]

Beta titanium (β-Ti) alloys have been widely used in aerospace and biomedical implants due to their specific strengths, low elastic modulus, and their resistance to corrosion. As β titanium alloy is a novel metastable, Ti-2Al-9.2Mo-2Fe (wt.%) alloy is essential to understand microstructural evolution and deformation behavior at room temperature to improve the strength–ductility balance. The deformation behavior and microstructural evolution of the Ti-2Al-9.2Mo-2Fe alloy during room-temperature deformation has been investigated via electron backscatter diffraction (EBSD) and electron channeling contrast imaging (ECCI). It was found that the β-solution-treated alloy exhibited a single β phase with a lower β stability. However, the α/β-solution-treated alloy exhibited a layered structure, consisting of fine α + β grain layers and coarse β grain layers, and the β in the coarse grain layer had a lower stability, but the β in the fine grain layer had a higher stability owing to the coexistence of α. The β-solution-treated alloy was mainly deformed via {332}<113> deformation twinning, thus showing very high ductility; uniform elongation of approximately 35%. The α/β-solution-treated alloy was deformed via two mechanisms, namely {332}<113> deformation twinning in the coarse grain layers and dislocation slip in the fine grain layers. The α/β-solution-treated alloy exhibited high strength with a lower ductility due to the small amount of deformation twinning. [ABSTRACT FROM AUTHOR]

SUS301L stainless steel joints with thickness of 2 mm were manufactured via the tungsten inert gas (TIG) and metal active gas arc (MAG) techniques, respectively. Electron backscatter diffraction results indicated that δ-ferrites with volume fraction of approximately 1.8% were formed in the weld seam of TIG joints, which was unbeneficial for the mechanical strength. By contrast, the microstructures were relatively fine and no δ-ferrites were formed in the MAG joints, showing a better microstructural quality compared with that of TIG joints. Nevertheless, the fatigue test results indicated that fatigue strength of TIG joints was higher compared with that of MAG joints. This was because that the lower weld reinforcement of TIG joints decreased the stress concentration at weld toe than that of MAG joints, which resulted in the better fatigue performance, implying that the fatigue behavior of welded joints was more influenced by the welding quality instead of microstructures. [ABSTRACT FROM AUTHOR]

The determination of orientation relationships in dual or multi-phase materials is very important in the field of interface engineering for the design of materials with tailored properties. In this work, a code is developed for the automated and statistical analysis of the orientation relationship of electron backscatter diffraction data. The code is applied to the example of Fe-Ni-(Si)-C alloys containing lenticular martensite and retained austenite, and it is shown that the orientation relationship (OR) corresponds to the Greninger–Troiano OR and that a statistically reliable investigation of the OR between the retained austenite and the related martensite variants is feasible using the code developed in this study. [ABSTRACT FROM AUTHOR]

The present work investigates the formation and microstructural and micro-mechanical characterization of the recast layer that formed on Inconel 718 alloy in the course of the wire electro-discharge machining (WEDM). The as-machined surface contains globules, shallow cracks, and re-deposition of molten materials, together with the elements from the decomposition of wire electrode and electrolyte, which does not exceed beyond the surface of the recast layer. Under presently investigated machining parameters, the recast layer was about 6.2 ± 2.1 µm thick. There was no presence of a heat-affected zone (HAZ), as otherwise indicated for other hard-to-cut materials. The transmission electron microscopy (TEM) and electron back-scattered diffraction (EBSD) investigations show that the microstructure of the recast layer is similar to that of bulk alloy. Micro-mechanical characterizations of the recast layer were investigated via in-situ micro-pillar compression on the micro-pillars fabricated on the recast layer. The strength of the superficial layer (1151.6 ± 51.1 MPa) was about 2.2 times higher than that of the base material (523.2 ± 22.1 MPa), as revealed by the in-situ micro-pillar compression. [ABSTRACT FROM AUTHOR]

Cobalt-based superalloys are common materials for the manufacturing of various components used in aerospace applications. Conventional cobalt-based superalloys with a unimodal grain structure generally exhibit low strength and ductility at high temperatures. A bimodal grain structure of a cobalt-based superalloy, Co–20Cr–15W–10Ni (CCWN), was designed to achieve both high strength and ductility at high temperatures. The deformation behavior and tensile properties of a CCWN alloy with unimodal fine-grain (FG), coarse-grain (CG), and bimodal (FG/CG) structures were investigated at 900 °C. The microstructures and substructures after high-temperature deformation were examined via electron backscatter diffraction (EBSD) and electron channeling contrast imaging (ECCI) to determine the deformation mechanisms. The microstructural observation showed that the bimodal grain structure consisted of FG and CG domains. During high-temperature deformation at 900 °C, the FG structure was mainly deformed by dynamic recrystallization (DRX), maintaining a similar FG structure. The CG structure was mainly deformed by DRV, resulting in a small amount of DRX grains and a large amount of dynamic recovery (DRV) grains. However, the bimodal grain structures were mainly softened via DRX and transformed into a new bimodal structure, ultrafine grain (UFG) and FG. The FG domains tended to deform via dislocations, and the CG domains via twinning. The high-temperature tensile tests revealed that the bimodal-structured alloy exhibited both higher strength and ductility than those of the alloy samples with unimodal FG or CG structure. This is associated with the newly developed UFG/FG structures in the bimodal grain-structured samples during high-temperature deformation. This work may provide new insight into the development of high-temperature alloys with bimodal grain structures. [ABSTRACT FROM AUTHOR]

As the demand for Advanced High Strength Steels (AHSS) increases, the need for faster and reliable ways to identify their microstructure and quantify the phase distribution becomes more evident. For some types of steels this can be done by a simple color etching and light optical microscopy (LOM) imaging. On the other hand, steels with more complex microstructural distribution require a combination of additional techniques, many of which are time-consuming, such as dilatometry or electron backscattering diffraction (EBSD). In this work, a combination of LOM and EBSD was used to quantify the microstructure of Complex-Phase steels. The methods used to process the data and distinguish the microconstituents in EBSD is explained and some exemplary results obtained in industrial steels are reported. Also, a previously used way to quantitatively compare the LOM and EBSD results is also shown to confirm the validity of the approach discussed in the present work. [ABSTRACT FROM AUTHOR]

AA6010 in the F temper was investigated using a Gleeble 3800 test rig across a range of temperatures (350–550 °C) and strain rates (1 × 10−1 s−1 1 × 101 s−1) to identify optimal forming conditions. Post-forming electron back-scattered diffraction analysis was conducted to identify the mechanisms responsible for the material formability. Optimal forming conditions were observed to be 500 °C and a strain rate of 1 × 10−1 s−1, with clear evidence of dynamic recrystallisation observed, this being the dominant mechanism responsible for the increased formability. Peak yield strength of 335 MPa was achieved using a rapid aging treatment of 205 °C for one hour. [ABSTRACT FROM AUTHOR]

During a series of high P-T experiments aimed at understanding the hydrothermal alteration of the REE,Ti silicate chevkinite-(Ce), three ThSiO 4 phases (thorite, huttonite, and an amorphous ThSiO 4 variety) were formed, showing a wide range of textures from small discrete grains to large-scale replacement of the chevkinite-(Ce). All three phases have compositions close to ThSiO 4 , except that the amorphous type contains small amounts of LREE (≤ 0.025 apfu) and inferred H 2 O. The three different forms have been confirmed by electron backscatter diffraction, which has also provided information on the microstructure of the crystals. The earliest phase to form was huttonite, composed of many randomly oriented microcrystals. This was later replaced by thorite via fluid-aided coupled dissolution-reprecipitation. The amorphous type formed both by apparent hydrous alteration of the original crystalline thorite and huttonite. The inferred sequence of events is compatible with thermodynamic constraints on the relative stability of thorite and huttonite. [Display omitted] • Thorium is highly soluble and mobile in high pH, transported as hydroxyl or F complexes. • Huttonite to thorite conversion: at constant P and T, due to Ostwald's kinetic effects. • ThSiO 4 formation sequence: huttonite, thorite, then an amorphous phase from hydrated thorite or huttonite. • ThSiO 4 rapidly turns amorphous, revealing a fluid-driven geochemical process distinct from metamictization. • REE arrangement in chevkinite influences thorite crystal orientation. [ABSTRACT FROM AUTHOR]

Electron backscatter diffraction (EBSD) patterns can exhibit Kikuchi bands with inverted contrast due to anomalous absorption. This can be observed, for example, on samples with nanoscale topography, in case of a low tilt backscattering geometry, or for transmission Kikuchi diffraction (TKD) on thicker samples. Three examples are discussed where contrast-inverted physics-based simulated master patterns have been applied to find the correct crystal orientation. As first EBSD example, self-assembled gold nanostructures made of Au fcc and Au hcp phases on single-crystal germanium were investigated. Gold covered about 12% of the mapped area, with only two thirds being successfully interpreted using standard Hough-based indexing. The remaining third was solved by brute force indexing using a contrast-inverted master pattern. The second EBSD example deals with maps collected at a non-tilted surface instead of the commonly used 70° tilted one. As TKD example, a jet-polished foil made of duplex stainless steel 2205 was examined. The thin part close to the hole edge producing normal-contrast patterns were standard indexed. The areas of the foil that become thicker with increasing distance from the edge of the hole produce contrast-inverted patterns. They covered three times the evaluable area and were successfully processed using the contrast-inverted master pattern. In the last example, inverted patterns collected at a non-tiled sample were mathematically inverted to normal contrast, and Hough/Radon-based indexing was successfully applied. • Zero tilt EBSD. • Improved conventional EBSD from nanostructures. • TKD on thick samples. • Inverted contrast patterns indexing. [ABSTRACT FROM AUTHOR]

• An overview focusing on the characterization of micro-residual stress is presented. • Advances in testing techniques including non-destructive and micro-destructive methods are summarized. • Challenges in practice and perspectives concerning the further improvement of characterization are proposed. Residual stresses are important factors affecting the performance and lifespan of components, among which the influence of micro-residual stress on crack propagation and fatigue property is no less than that of macro-residual stress, so it cannot be underestimated in materials design, forming and processing, life prediction as well as failure analysis. However, the accurate characterization of micro-residual stress is still facing many challenges, and the interaction between micro-residual stress and microstructures has yet been clearly understood. In view of this, the latest progress in the characterization methods such as electron backscattered diffraction, focused ion beam-digital image correlation, nanoindentation, among others, in mapping the micro-residual stress is summarized, including the testing principle, scope of application, measurement accuracy, along with the corresponding limitations. In addition, the trends for techniques in probing micro-residual stress are also proposed with the aim of extending extra vision for further improving the measurement accuracy and systematic research on residual stresses on microscopic scale. [ABSTRACT FROM AUTHOR]

The complex deformation of magnesium (Mg) and its alloys has been the focus of many studies in lightweight technologies. In this paper, spherical micro-indentation tests followed by post-test electron microscopy were carried out on large grain pure Mg to isolate the effects of crystal orientation on the activation of deformation along different slip or twinning systems. Both pre- and post-indentation crystal orientations were measured using electron backscatter diffraction (EBSD). The pre-indentation orientations were mapped into a crystal plasticity finite element (CPFE) model to further analyze the results. It is shown that the resulting deformation twinning and the degree of indentation-induced misorientation were strongly correlated with the crystal orientation in the region of the indentation. Depending on the crystal orientation, multiple waves of basal slip were observed to form asymmetrically around the indents. These slip bands lead to more than 12° lattice rotations that are captured by CPFE modeling. For the first time, it is shown that indentation can lead to significant out-of-plane displacement field that can induce twin nucleation at the interface of far-field (>100 μm) neighbouring grains. CPFE simulations indicate that maintaining far-field strain compatibility leads to the nucleation of twins rather than a slip transfer or slip-induced twinning mechanism. • CPFE and micro indentation are used to characterize deformation mechanisms of pure magnesium. • EBSD is used to measure orientation distribution before and after indentation within individual grains. • Asymmetric plastic deformation occurs with the formation of slip bands, twins, and misorientation fields around indents. • A new mechanism for nucleation of twins in neighbouring grains is discovered. • Numerical modeling shows this nucleation results from out-of-plane displacement, not a slip-induced twinning. [ABSTRACT FROM AUTHOR]

The microstructural evolution of SK85 pearlitic steel cold-rolled up to a 90% rolling reduction was characterized by scanning electron microscopy with electron backscattered diffraction (EBSD) and X-ray diffraction (XRD). SK85 steel exhibits excellent cold rolling performance. The interlamellar spacing of pearlite is refined obviously and a tensile strength of 2318 MPa can be reached for SK85 steel after 90% rolling reduction, an increase of 83% from 1264 MPa before rolling. The EBSD observation indicates that the {001} <110> texture becomes pronounced at a 90% rolling reduction in cold-rolled Sk85 steel. A propagation and multiplication of dislocations occur during rolling as the kernel average misorientation (KAM) angles significantly increase from 0.72° to 2.11°. The XRD analysis reveals that bcc ferrite is transformed into a bct structure at a 90% rolling reduction. The strengthening mechanism was discussed. [ABSTRACT FROM AUTHOR]

Complex microstructures of zircon recrystallisation have been discovered in igneous and metamorphic zircons from the Jack Hills Metasedimentary Belt in Western Australia, and the granitic injection complex of Harris in north-west Scotland. Cathodoluminescence (CL), electron backscatter diffraction (EBSD) and wavelength dispersive spectroscopy (WDS) analysis reveal that recrystallisation in the studied zircons is often characterised by (1) translation, bending and fading of the oscillatory zoning; (2) structural recovery of the zircon; (3) an enrichment in Hf and depletion in Y in recrystallised zircon; and (4) the formation of a recrystallisation interface with a minor (<2°) misorientation. A new, composite recrystallisation model in which trace element and dislocation migration occurs shortly after crystallisation during magmatic cooling and pipe diffusion along dislocation arrays formed by the accumulation of dislocations allows enhanced diffusion to enrich Hf and leach U, Pb and Y. After the recrystallisation event, subsequent metamictization of primary zircon (typically with oscillatory zoning) creates zones that can structurally recover through a diffusion-reaction re-equilibration mechanism, resulting in further trace-element mobility. These mechanisms can create complex microstructures in zircons, suggesting that a detailed understanding of the crystallisation and recrystallisation history of a zircon may be required to accurately interpret its U-Pb ages. [ABSTRACT FROM AUTHOR]

The mechanical response of polycrystalline materials significantly depends on the details of the microstructure. For example, different spatial grain size distributions can lead to different mechanical response. Deformation produces a hardened material and a loss of ductility, while annealing makes the metal softer as a direct result of the loss of dislocations via recovery and recrystallization. However, introducing a limited fraction of heterogeneity into the microstructures can be useful in balancing the typical tradeoff between strength and ductility even without the need to perform a subsequent restoration process (recrystallization). The objective of this work is to devise computational microstructural evolution tools to design heterogeneous microstructures comprised of rolled and equiaxed structures simultaneously. Afterward, these heterogeneous structures are experimentally produced in commercial purity Al by a simple rolling process on a complex sample geometry and mechanically tested (tension test). Electron backscatter diffraction (EBSD) measurements are made to validate the computer simulation results. [ABSTRACT FROM AUTHOR]

The present study reports the hot deformation behavior, microstructural evolution, and the alloying effects of refractory elements (Ta, Mo, W) in Ni 48.6 Al 10.3 Co 17 Cr 7.5 Fe 9 Ti 5.8 Ta 0.6 Mo 0.8 W 0.4 (at. %) high entropy alloy (HEA). The vacuum arc melted specimens were characterized using a scanning electron microscope, X-ray diffractometer, and Differential scanning calorimetry, which revealed the two-phase structure consisting of γ′ precipitates embedded in the γ matrix. The Energy Dispersive Spectroscopy analysis in a scanning electron microscope revealed that Mo and W partitioned into the dendritic region (K Mo = 1.23 and K W = 1.28) while Ta is found to be partitioned in the interdendritic region composed of mostly γ′ precipitates (K Ta = 0.67). Further, the specimens were subjected to hot deformation in the 800 °C - 1100 °C temperature range at the strain rate of 0.01s−1. The maximum flow strength was around 278 MPa and 183 MPa at 1050 °C and 1100 °C, respectively. The flow behavior is correlated with the microstructure evolution, which is characterized using electron backscattered diffraction (EBSD). In the cases of hot deformation below 1000 °C, localized plastic flow in the form of shear bands developed in coarse grain microstructure, whereas fine grains evolved due to dynamic recrystallization (DRX) in the sample deformed above 1000 °C. Further, the role of refractory elements in retaining high-temperature flow strength has been discussed. [ABSTRACT FROM AUTHOR]

In this work, extruded plates made of Mg-13.9Gd-0.45Zr (wt%) alloy, without any significant texture, were rolled at 475 °C along the extrusion direction (ED) and the extrusion transverse direction (ETD) to investigate the evolution of texture during the traditional hot rolling process. The microstructure and texture evolution during the rolling process were characterized and analyzed by electron backscattered diffraction (EBSD). The results reveal that a kind of rare earth (RE) texture that split from the normal direction (ND) towards the rolling transverse direction (RTD) can be formed by the prismatic slip at low strain. However, with the strain increasing, the RE texture gradually transforms into a basal texture since the extensive activation of basal dislocations and pyramidal < c + a > dislocations, especially pyramidal < c + a > dislocations. This transformation solely depends on the rolling reduction, which underscores the significance of strain as a pivotal factor in the texture modification. ● The formation of RE texture in GK140 during the rolling process is dominated by prismatic < a > slips. ● The activation of pyramidal < c+a > and basal < a > slip in GK140 can transform the RE texture into a basal texture. ● The transformation of the RE texture into a basal texture in GK140 alloy is strain-controlled. [ABSTRACT FROM AUTHOR]

Electron backscatter diffraction (EBSD) was used to determine the orientation of mechanically twinned grains in Carrara marble experimentally deformed to a small strain (≤4%) at room temperature and at a moderate confining pressure (225 MPa). The thicknesses of deformation twins were mostly too small to permit determination of their orientation by EBSD but it proved possible to measure their orientations by calculating possible twin orientations from host grain orientation, then comparing calculated traces to the observed twin traces. The validity of the Turner & Weiss method for principal stress orientations was confirmed, particularly when based on calculation of resolved shear stress. Methods of paleopiezometry based on twinned volume fraction were rejected but a practical approach is explored based on twin density. However, although twin density correlates positively with resolved shear stress, there is intrinsic variability due to unconstrained variables such as non-uniform availability of twin nucleation sites around grain boundaries that imposes a limit on the achievable accuracy of this approach. [ABSTRACT FROM AUTHOR]

Deformation is a near ubiquitous process that is observed within nearly all naturally forming rocks. Electron backscatter diffraction (EBSD) is a technique that enables slip‐systems (a form of plastic deformation) to be inferred from intracrystalline misorientations at a comparable scale to the representative CPO analysis (≥300 crystals for the nakhlites). Extensive laboratory and studies on naturally occurring samples have identified preferential mantle condition extrinsic parameters for specific slip‐system signatures within olivine and clinopyroxene. Intracrystalline misorientation patterns for olivine and augite (high Ca‐clinopyroxene) for 16 different Martian nakhlite meteorites (21 sections) were analyzed and assessed against these known parameters. Investigation of high and low deformation regions within the nakhlites revealed a shift in intracrystalline misorientation patterns for 10 of the 21 sections. Interpreted as both shock (high deformations) and emplacement (low deformation) signatures, the observed variations in deformation patterns for the two main regimes of deformation indicate heterogeneous sampling of the nakhlite source crater. Our findings indicate that shock deformation is prevalent throughout the nakhlites, and that great care needs to be taken when interpreting intracrystalline misorientations of crystals within apparent lower deformation regions. Plain Language Summary: Clinopyroxene and olivine are important minerals for studying igneous processes on Mars and Earth (from the surface to the upper mantle). Here, clinopyroxene and olivine intracrystalline misorientation patterns—deformational movement within a crystal—were investigated in a group of meteorites from Mars using the specialist microscopic technique of electron backscatter diffraction (EBSD). The nakhlites are mafic rocks representing the largest collection of rocks from a singular—but as yet unknown—location on Mars. Combined intracrystalline misorientation patterns for both olivine and clinopyroxene reveal nine different shock deformation signatures for the nakhlites indicating that they were sourced from multiple locations within the ejection crater. Nonshock related deformation can also be observed but tends to be masked by the dominance of shock deformation features even in low deformation regions. Key Points: Electron backscatter diffraction reveals shock‐derived deformation to mask nonshock deformation even in low deformation regions in the nakhlitesIntracrystalline misorientation patterns indicate nine distinct derived deformation signatures for 16 nakhlitesIntracrystalline misorientation patterns are identified within low deformation regions interpreted as emplacement deformation [ABSTRACT FROM AUTHOR]

Vertex method to simulate grain growth usually starts with the use of a homogeneous theoretical microstructure obtained by Voronoi tessellation. This microstructure does not represent real materials where the grains are not homogeneously distributed in terms of size and orientation. In order to take into account these inhomogeneities, and consequently correctly describe the grain growth process, in this paper a vertex simulation begins with the use of the experimental microstructure as the initial data. To facilitate the simulation procedure as well as the analysis of the result, instead of using only the network of grain boundaries and vertices to represent the microstructure in the standard vertex model, we use a hexagonal lattice to discretize the physical space. Each site of the hexagonal lattice is assigned three Euler angles that represent the grain orientation at that lattice site. [ABSTRACT FROM AUTHOR]

An in situ tensile test of the ring-rolled GH4169 alloy is performed to investigate the plastic deformation behavior at the micro level. Slip system activations are identified by slip traces captured by a scanning electron microscope and lattice orientation data acquired by electron backscattered diffraction. Our results demonstrated that the fraction of low-angle grain boundaries gradually increased upon tensile deformation, and the misorientation evolution in the grain interior was severely inhomogeneous. The Schmid factors at the grains of interest are calculated for comparison with the actual activated slip systems. Most of the slip system activation coincides with the Schmid law, as opposed to the initiation of other potential slip systems at some grains. [ABSTRACT FROM AUTHOR]

A series of experiments combining deformation, irradiation damage, and high temperature have been carried out. First, small tensile samples (less than 500 μm thick) will be subjected to constant deformation (supported by a suitably instrumented mini tensile machine) during irradiation of Fe ions at different temperatures (room temperature, RT, and 450 °C). Subsequently, FIB (Focused Ion Beam) samples will be extracted from the irradiated specimen, and an EBSD (Electron Backscatter Diffraction) and TEM (Transmission Electron Microscopy) characterisation will be carried out. The material studied is a high purity Fe- BCC model alloy. The objective is to determine the possible synergy between the effect of deformation and temperature during irradiation on the evolution of radiation-induced defects, whereby the chosen dose allows us to determine a potential bias for the generation of such defects. [ABSTRACT FROM AUTHOR]

The current paper is related to the study of the microstructure and texture of two machinable lead-free brass alloys, namely CuZn42 (CW510L) and CuZn38As (CW511L), which were evaluated in the as-drawn and post heat treated condition. Electron backscatter diffraction (EBSD) was employed for the examination of the brass rods' crystallographic properties in order to correlate the effect of post processing heat treatment on the evolution of phase structure and texture towards the interpretation of dynamic (impact) fracture properties. It is shown that α- and β-phase volume fractions, mean grain size, and grain boundary misorientation are the most influential factors altering the fracture resistance of single- and dual-phase brass alloy rods. The role of grain boundary engineering, through the formation of coincidence site lattice (CSL) boundaries and their evolution during thermomechanical processing, is of major importance for the design of the mechanical behaviour of new eco-friendly machinable brass alloys. [ABSTRACT FROM AUTHOR]

The Yeba ductile shear zone is located on the southern margin of the middle Gangdese magmatic belt and southeast of Lhasa, China. In this paper, we systematically investigate the structural deformation history in the Yeba Group and provide the kinematics, strain pattern, mean vorticity number and temperature environment of the Yeba ductile shear zone. Three tectonic events are identified in the Yeba Group of the study area. The Yeba shear zone represents the late stage of the northward subduction of the Neo-Tethys Ocean (D1 stage, 94–85 Ma). Since the collision of the Indian and Eurasian plates, principal compressive stress (σ1) in the north–south direction was generated in the Yeba Group and formed composite folds (D2 stage, ~ 50 Ma). The D3-stage structural deformation event of the Yeba Group in the study area is represented by the Woka ductile shear zone (22.38–14.6 Ma). Electron backscattering diffraction and chlorite geothermometry demonstrate that upper greenschist facies (213–295 °C) and lower greenschist facies (400–550 °C) conditions developed in the Yeba shear zone. Finite strain measurements of the Yeba ductile shear zone indicate that almost all deformed rocks exhibit an oblate ellipsoid consistent with near-flattening strain. Kinematic vorticity analysis of the Yeba shear zone yielded values (Wm) of 0.49–0.78, indicating a bulk general shear deformation regime with a combination of 58% pure shear and 42% simple shear. The kinematic vorticity number (58% pure shear), flattening strain pattern, and presence of opposite indicators in the same mylonitic foliation support the occurrence of a transpressive structure. [ABSTRACT FROM AUTHOR]

The effect of gnomonic distortion on orientation indexing of electron backscatter diffraction patterns is explored through simulation of electron diffraction patterns for sample‐to‐detector geometries associated with transmission Kikuchi diffraction (TKD) and electron backscatter diffraction (EBSD). Simulated data were analysed by computing a similarity index for both Hough transformed data and simulated patterns to determine the sensitivity of each method for detecting subtle differences in the effect of gnomonic distortions on electron diffraction patterns. These results indicate that the increased gnomonic distortions in electron diffraction patterns for a TKD geometry enhance the sensitivity for detecting subtle differences in interband angles. Additionally, the utilisation of a Hough transform‐based indexing approach further enhances the sensitivity. Electron backscatter diffraction (EBSD) and transmission Kikuchi diffraction (TKD) have become vital tools for studying materials. These probes provide information about how locally arranged. EBSD and TKD utilise different experimental configurations that have impacts the measured data. The projection of the electron diffraction Ewald's sphere onto the face of the detectors results in Gnomonic distortions, and the selection of experimental configuration affects the magnitude of these distortions. In this work we used simulated dynamical electron diffraction patterns (EDPs) to understand the how differences in the EBSD and TKD experimental configurations impacts Gnomonic distortions and how these distortions effect the sensitivity of each method for detecting subtle differences in interband angles. These results indicate that the increased gnomonic distortions in electron diffraction patterns for a TKD geometry enhance the sensitivity for detecting subtle differences in interband angles. These results also suggest that a traditional Hough transform approach for indexing EDP data is less sensitive to detecting slight deviations than direct analysis of EDPs. [ABSTRACT FROM AUTHOR]

Recently, variational methods were successfully applied for computing the optical flow in gray and RGB-valued image sequences. A crucial assumption in these models is that pixel-values do not change under transformations. Nowadays, modern image acquisition techniques, such as electron backscatter diffraction (EBSD) used in materials science, can capture images with values in nonlinear spaces. Here, the image values belong to the quotient space SO(3)/\scrS of the special orthogonal group modulo the discrete symmetry group of the crystal. For such data, the assumption that pixel-values remain unchanged under transformations appears to be no longer valid. Hence, we propose a variational model for determining the optical flow in SO(3)/\scrS -valued image sequences, taking into account the dependence of pixel-values on the transformation. More precisely, the data is transformed according to the rotation part in the polar decomposition of the Jacobian of the transformation. To model nonsmooth transformations without obtaining so-called staircasing effects, we propose using total generalized variation, such as prior. Then, we prove existence of a minimizer for our model and explain how it can be discretized and minimized by a primal-dual algorithm. Numerical examples illustrate the performance of our method. [ABSTRACT FROM AUTHOR]

• Combined microstructural and U-Pb chronology of baddeleyite within shergottites. • Widespread reversion from orthorhombic zirconia polymorphs revealed by microstructures. • No link between microstructure and U-Pb chronology; ages date crystallization. • Insufficient heating during shock metamorphism to induce Pb mobility. • New ages of NWA 7257 and NWA 8679 of 195 ± 15 Ma and 220 ± 23 Ma, respectively. Baddeleyite (monoclinic; m -ZrO 2) is a widespread accessory phase within shergottites. However, the effects of shock loading on baddeleyite U-Pb isotopic systematics, and therefore its reliability as a geochronometer within highly shocked lithologies, are less well constrained. To investigate the effects of shock metamorphism on baddeleyite U-Pb chronology, we have conducted high-resolution microstructural analysis and in-situ U-Pb isotopic measurements for baddeleyite within enriched basaltic shergottites Northwest Africa (NWA) 7257, NWA 8679 and Zagami. Electron backscatter diffraction (EBSD) analyses of baddeleyite reveal significant microstructural heterogeneity within individual thin sections, recording widespread partial to complete reversion from high-pressure (≥3.3 GPa) orthorhombic zirconia polymorphs. We define a continuum of baddeleyite microstructures into four groupings on the basis of microstructural characteristics, including rare grains that retain magmatic twin relationships. Uncorrected U-Pb isotopic measurements form Tera-Wasserburg discordia, yielding new 238U-206Pb discordia ages of 195 ± 15 Ma (n = 17) for NWA 7257 and 220 ± 23 Ma (n = 10) for NWA 8679. Critically, there is no resolvable link between baddeleyite microstructure and U-Pb isotope systematics, indicating negligible open-system behaviour of U-Pb during zirconia phase transformations. Instead, we confirm that high post-shock temperatures exert the greatest control on Pb mobility within shocked baddeleyite; in the absence of high post-shock temperatures, baddeleyite yield robust U-Pb isotope systematics and date the age of magmatic crystallization. Low bulk post-shock temperatures recorded within Zagami (≤220 °C), and suggested within NWA 7257 and NWA 8679 by baddeleyite microstructure and other petrological constraints, confirm that the previously derived baddeleyite age of Zagami records magmatic crystallization, and provide greater age diversity to 225 Ma to 160 Ma enriched shergottites. While our data yield no resolvable link between microstructure and U-Pb isotopic composition, we strongly recommend that microstructural analyses should represent an essential step of baddeleyite U-Pb chronology within planetary (e.g., martian, lunar, asteroidal) and shocked terrestrial samples, allowing full contextualisation prior to destructive isotopic techniques. Microstructurally constrained in-situ U-Pb analyses of baddeleyite thus define new opportunities for the absolute chronology of martian meteorites and, more broadly, shocked planetary materials. [ABSTRACT FROM AUTHOR]

We discuss a refined simulation approach which treats Kikuchi diffraction patterns in electron backscatter diffraction (EBSD) and transmission Kikuchi diffraction (TKD). The model considers the result of two combined mechanisms: (a) the dynamical diffraction of electrons emitted coherently from point sources in a crystal and (b) diffraction effects on incoherent diffuse intensity distributions. Using suitable parameter settings, the refined simulation model allows to reproduce various thickness‐ and energy‐dependent features which are observed in experimental Kikuchi diffraction patterns. Excess‐deficiency features are treated by the effect of gradients in the incoherent background intensity. Based on the analytical two‐beam approximation to dynamical electron diffraction, a phenomenological model of excess‐deficiency features is derived, which can be used for pattern matching applications. The model allows to approximate the effect of the incident beam geometry as a correction signal for template patterns which can be reprojected from pre‐calculated reference data. As an application, we find that the accuracy of fitted projection centre coordinates in EBSD and TKD can be affected by changes in the order of 10−3–10−2 if excess‐deficiency features are not considered in the theoretical model underlying a best‐fit pattern matching approach. Correspondingly, the absolute accuracy of simulation‐based EBSD strain determination can suffer from biases of a similar order of magnitude if excess‐deficiency effects are neglected in the simulation model. [ABSTRACT FROM AUTHOR]

In the present work, the combined effect of constrained groove pressing (CGP) followed by cold rolling on the microstructural and mechanical behavior of ARMCO Fe is investigated. Annealed ARMCO Fe sheets are CGP processed up to 3 cycles and 4 cycles followed by cold rolling reduction up to 60%, 75% and 90%, thereby imposing strain up to ~ 7. Backscattered scanning electron microscope (BSE-SEM) studies complemented by transmission electron microscope analysis indicated significant grain refinement resulting in ~ 0.5-0.7 μm sized structure after CGP processing. Microstructural evolution studied employing electron backscattered diffraction, divulged continuous dynamic recrystallization-driven grain refinement manifested by low-angle grain boundaries bounded cell structures and highly misoriented high-angle boundary bounded grains after CGP processing. Combining cold rolling followed by CGP revealed further grain refinement up to ~ 0.3 μm characterized by elongated grain structure. Tensile behavior indicates substantial improvement in yield strength by nearly ~ 3 times after CGP processing corroborating to the observed grain refinement with a concomitant decrease in ductility. Combined with cold rolling, the yield strength further improved with increasing cold rolling reduction and maximized to ~ 483 MPa from an initial strength of 90 MPa in the annealed condition. [ABSTRACT FROM AUTHOR]

Symmetry analysis of the Kikuchi pattern is helpful to determine the crystal structure, and can significantly reduce the screening range of phase identification, thereby improving the accuracy and reliability of phase identification in electron backscatter diffraction (EBSD). Accurately identifying the symmetry axis from the Kikuchi pattern is the primary task of symmetry analysis. In this study, a new method was proposed to identify symmetry axes in Kikuchi patterns with the aid of reciprocal vectors. Taking the Kikuchi patterns of single‐crystal silicon as a typical example, a method for drawing reciprocal vectors after strict projection correction is introduced. The complex task of identifying the symmetry axis is transformed into an intuitive judgment of the geometric relationship between reciprocal vectors, thus greatly simplifying the process. This method successfully elucidated information on six Kikuchi poles in three single‐crystal silicon Kikuchi patterns, including 3‐fold axes, 4‐fold axes and asymmetric axes. The method can also distinguish between a 3‐fold axis and an analogous 3‐fold axis despite their only slight differences. [ABSTRACT FROM AUTHOR]