Exploring the Structure–Property Relationship in Spheroidized C45EC Steel Using Full Phase Crystal Plasticity Numerical Simulations

Constructing micro-mechanical representative volume element of medium Mn steel from EBSD data

In this work, the authors describe procedures to prepare the surface of close-spaced sublimation CdTe thin films necessary for producing good electron backscatter diffraction (EBSD) data. They found that polishing resulted in an amorphous layer on the surface and no Kikuchi pattern; however, ion-beam milling produced a relatively flat and good-quality surface, resulting in high-quality patterns and, consequently, excellent EBSD data. The authors used a combination of polishing and ion-beam milling or etching to study the crystalline structure of the CdTe film at different depths. They also used EBSD, in conjunction with other analytical techniques, to investigate the effects of the CdCl2 treatment, performed at different temperatures and times, on the recrystallization process of physical vapor deposition CdTe thin films. The authors found that the untreated films were ⟨111⟩ oriented, with grain sizes smaller than 1μm. The CdCl2 at 350 °C produced partially recrystallized films, whereas treatments at 400 °C or 420 °C produced completely recrystallized films, with no texture, and grains with grain sizes varying from about 1μm to more than 40μm. These films were so flat that good EBSD data could be obtained without any surface preparation. Atomic force microscopy and scanning electron microscopy showed that large grains had different morphologies than smaller grains, and EBSD showed that these large grains had ⟨111⟩ texture. These results indicate that the (111) surface is the lowest energy surface in these films and, consequently, ⟨111⟩-oriented grains grow at the expense of grains oriented in less-favorable directions. Regardless of the deposition method and treatment, the CdTe films have a high density of 60° ⟨111⟩ twin boundaries.

Electron backscatter diffraction scans are an important experimental input for microstructure generation and homogenization. Multiple electron backscatter diffraction scans can be used to sample the uncertainty in orientation distribution function: both point to point within a specimen as well as across multiple specimens that originate from the same manufacturing process. However, microstructure analysis methods typically employ only the mean values of the orientation distribution function to predict properties, and the stochastic information is lost. In this work, analytical methods are developed to account for the uncertainty in the electron backscatter diffraction data during property analysis. To this end, a linear smoothing scheme is developed in the Rodrigues fundamental region to compute the orientation distribution function from the electron backscatter diffraction data. The joint multivariate probability distributions of the orientation distribution function are then modeled using a Gaussian assumption. The uncertainty in engineering properties that are obtained by homogenization are also computed. It is shown that the uncertainty in nonlinear properties can be analytically obtained using direct transformation of random variables in the homogenization approach.

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.

Ten years ago electron backscatter diffraction (EBSD) became available to a wider group active in materials research. This paper highlights some of the more significant developments in camera technology and software developments that have arisen since then. The use of slow-scan charge couple device cameras for phase identification and rapid determination of orientation image micrographs is reviewed. The current limiting spatial resolution of the technique is shown to be less than 10 nm. A procedure for improving lattice spacing measurement by utilizing the full resolution of the camera is described with experimental measurements on silicon and nickel showing relative errors of plus/minus 3%. An investigation of partially recrystallized aluminium shows how the recrystallized fraction can be extracted with confidence but that the mapping of substructure in the highly deformed regions is questionable. Phase identification is described for complex cases in which the phase data tabulated in standard databases do not correspond to what is observed in the EBSD patterns. Phase mapping in a complex mineral in which chemical data and EBSD data are collected simultaneously is shown to be improved by recording both the chemical and the EBSD data into computer memory and proceeding with the phase discrimination and orientation measurement in off-line analysis.

Electron backscatter diffraction (EBSD) data yield plentiful information on microstructure and texture of natural as well as experimentally produced mineral and rock samples. For instance, the characterization of microstructures and textures by EBSD allows for the evaluation of phase equilibria. Furthermore, determination of the preferred orientations of crystals using EBSD yields constraints on deformation mechanisms and history of the minerals/rocks. The latter affects bulk-rock properites, for example, through the relation between lattice preferred orientation and electrical conductivity and seismic anisotropy. EBSD is also applied to advance our understanding of various phenomena such as seismic wave attenuation in the Earth deep interior and its relation to the presence of interfacial small degrees of melt fractions, or free fluid phases. In standard EBSD software solutions, the original EBSD patterns are rarely saved and indexing routines result in many artifacts, such as pseudo-symmetry or unindexed pixels at interfaces that may be misinterpreted as amorphous material, such as a melt. Here we report the first application of the dictionary indexing (DI) approach proposed by Chen et al. (2015), an alternative indexing routine, which we extended to be applicable to multiphase geologic materials. The DI method is independent of the EBSD system, and thus of the used detector/software. The DI routine generates simulated EBSD patterns for all possible crystal orientations, taking the sample composition and experimental setups into account. The resulting pattern database is called a dictionary. The experimental electron backscattering pattern (EBSP) images are indexed by comparing them to the dictionary using a dot-product algorithm. We evaluate the new DI method in comparison to standard routines and highlight advantages and disadvantages. To test and compare the DI’s reliability and performance, we apply the routine to two scientifically challenging samples: (1) A nominally anhydrous (“dry”) residual eclogite composed of garnet (cubic), clinopyroxene (monoclinic) and an amorphous melt, where the different degrees of hardness of the phases cause surface topology; and (2) a pure forsterite (olivine) polycrystalline sample produced by vacuum sintering. The acquired EBSD patterns are of low quality for the latter as a result of fast data acquisition to reduce the on-line machine time. We conclude that the new DI method is highly precise and surpasses the performance of previously available methods, while being computer time and computer memory consuming. We find that the DI method is free of pseudo-symmetry-related problems. Interpolation of data becomes obsolete and high reproducibility is obtained, which minimizes the operator impact on the final data set. The latter is often caused by applying several cleaning steps on EBSD maps with low indexing fraction. Finally, much higher scientific integrity is ensured by image collections as described above, which requires that all patterns are saved. This in turn allows later re-analyses if required. The DI routine will help to achieve more reliable information on interface properties of geological samples, including amorphous materials, and thus in the long run help to improve the accuracy of large-scale Earth mantle process models.

Effect of unusual texture on tension-compression asymmetry for Mg-RE alloy by viscoplastic self-consistent modeling

Seismic velocities, anisotropy and deformation in Siberian cratonic mantle: EBSD data on xenoliths from the Udachnaya kimberlite

Acoustical holography (volume 7) — Recent advances in ultrasonic visualization: Edited by Lawrence W. Kessler Plenum Press, New York and London (1977), xiii + 654 pp, $35.40

Texture evolution in deformed AZ31 magnesium sheets: Experiments and phase-field study

Investigation of deformation mechanisms in an advanced FeCrAl alloy using in-situ SEM-EBSD testing

To improve component design, the fundamental understanding of the fatigue behaviour of gas turbine materials is essential. Since Ni-alloys exhibit pronounced elastic anisotropy, the local grain orientation strongly affects the stress and strain distribution in the material under mechanical loadings. This work addresses the characterisation of anisotropic elastic–plastic deformation and its consequences for crack initiation of nickel-base superalloy IN617 under tensile loading. Samples were loaded in situ in a scanning electron microscope (SEM) to correlate the deformation behaviour with the grain structure and the grain orientation determined by electron backscatter diffraction (EBSD) measurements. To calculate the resulting stresses and strains, the EBSD data were used to develop a model by finite element method (FEM) considering the grain structure and orientation. The results of the elastic–plastic finite element (FE) simulation were compared with the theories of the E⋅m model based on the Schmidt factor (m) and anisotropic Young’s modulus (E). A mathematical image registration method called “optical flow method” (OFM), which is capable to calculate the transformation of EBSD measuring points during deformation, was applied to the EBSD data. The strains calculated by the optical flow method and by FE simulation were compared for two samples. The findings revealed large strains in the later crack initiation area found in both the OFM and FEM. The developed FEM model was verified by the successful correlation of hypotheses of the E·m model with the simulated mechanical behaviour. Furthermore, the impact of the microstructural neighbourhood on the mechanical behaviour was emphasised.Graphical

The oxygen content during the intermediate and final stages of sintering can have a strong effect on the microstructural evolution of oxide fuels. Two depleted urania (d-UO2.0 and d-UO2.14) samples, sintered up to a theoretical density of 90%, were serial sectioned using a focused ion beam and characterized with electron backscatter diffraction (EBSD). The EBSD data were used to make three-dimensional reconstructions of the microstructures to evaluate their characteristics at an intermediate stage of sintering. The oxygen content was found to affect grain shape and grain boundary (GB) mobility, as curved and elongated grains were observed in UO2.0, as well as stronger pore-GB interactions, which is an indication that microstructure was less evolved in UO2.0. Both samples presented a similar fraction ([approximate]20%) of special, coincident site lattice boundaries, with larger amounts of Σ3n GBs, and a rather large fraction of Σ11 GBs for UO2.14. Crystallographic GB planes were also determined to study the distributions of all GB parameters. The UO2.0 sample had a large fraction of GB planes close to the Σ3 twinning planes, which suggests that lower-energy interfaces are used to minimize energy in this sample, potentially due to lower overall GB mobility as compared to UO2.14.

Grain size and orientation affected deformation inhomogeneity and local damage of hot-deformed Al-Zn-Mg alloy

Evaluation of stored energy in cold-rolled steels from EBSD data