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Background: Recent improvements in spatial resolution and measurement sensitivity for high-resolution digital image correlation (HR-DIC) now provide an avenue for the quantitative measurement of deformation events and capturing the physical nature of deformation mechanisms. However, HR-DIC measurements require significant time due to scanning electron image acquisition; such a limitation prevents the widespread use of HR-DIC for material characterization. Objective: Apply a novel SEM acquisition technology to enhance HR-DIC measurements for high throughput applications. Methods: Multi-beam SEM technology is employed to image an entire gauge length at once at high resolution and at nearly a hundredfold acceleration of typical HR-DIC image acquisition, even when automated stage movement and image acquisition are employed. These images were fed into a discontinuity-tolerant HR-DIC software to determine slip localization induced by non-metallic inclusions and grain structure. Results: Slip localization was able to be analyzed to an unprecedented level, with over 210,000 slip bands able to be investigated, with the most intense slip localizing near and parallel to twin boundaries and in the vicinity of non-metallic inclusion clusters. Additionally, secondary slip activation and grain boundary shearing by intense dislocation pileups are observed to reduce slip amplitude near and parallel to twin boundaries. Conclusions: By performing HR-DIC in conjunction with a multi-beam SEM, high-throughput measurements of large field-of-view, high-resolution images were able to be performed in a timely manner. These measurements provided an immense number of slip events for statistical analysis to be performed on to relate to microstructural features. [ABSTRACT FROM AUTHOR]

The development of high-fidelity mechanical property prediction models for the design of polycrystalline materials relies on large volumes of microstructural feature data. Concurrently, at these same scales, the deformation fields that develop during mechanical loading can be highly heterogeneous. Spatially correlated measurements of 3D microstructure and the ensuing deformation fields at the micro-scale would provide highly valuable insight into the relationship between microstructure and macroscopic mechanical response. They would also provide direct validation for numerical simulations that can guide and speed up the design of new materials and microstructures. However, to date, such data have been rare. Here, a one-of-a-kind, multi-modal dataset is presented that combines recent state-of-the-art experimental developments in 3D tomography and high-resolution deformation field measurements. Measurement(s) 3D grain structure and grain orientations • Surface deformation fields Technology Type(s) Electron backscatter diffraction (EBSD) • Scanning electron microscope (SEM) • TriBeam microscope • high resolution digital image correlation Factor Type(s) applied macroscopic strain • crystallographic orientation Sample Characteristic - Organism nickel superalloy Inconel 718 Sample Characteristic - Environment mechanical deformation [ABSTRACT FROM AUTHOR]

A multi-modal data-merging framework that enables the reconstruction of slip bands in three dimensions over millimeter-scale fields of view is presented. The technique combines 3D electron back-scattered diffraction (EBSD) measurements with high-resolution digital image correlation (HR-DIC) information collected in the scanning electron microscope (SEM). A typical merging workflow involves the segmentation of features within the strain field (slip bands, deformation twins) and the microstructure (grains), alignment of datasets and the projection of slip bands into the 3D microstructure, using the knowledge of the local crystallographic orientation. This method is demonstrated in two materials: a face-centered cubic (FCC) nickel-base superalloy and hexagonal close-packed (HCP) titanium alloy. [ABSTRACT FROM AUTHOR]

This paper details the creation of experimental and computational frameworks to capture high-resolution, microscale deformation mechanisms and their relation to microstructure over large (mm-scale) fields of view. Scanning electron microscopy with custom automation and external beam control was used to capture 209 low-distortion micrographs of 360 μm × 360 μm each, that were individually correlated using digital image correlation to obtain displacement/strain fields with a spatial resolution of 0.44 μm. Displacement and strain fields, as well as secondary electron images, were subsequently stitched to create a 5.7 mm × 3.4 mm field of view containing 100 million (7678 × 13,004) data points. This approach was demonstrated on Mg WE43 under uniaxial compression, where effective strain was shown to be relatively constant with respect to distance from the grain boundary, and a noticeable increase in the effective strain was found with an increase in the basal Schmid factor. The ability to obtain high-resolution deformations over statistically relevant fields of view enables large data analytics to examine interactions between microstructure, microscale strain localizations, and macroscopic properties. [ABSTRACT FROM AUTHOR]

A correlation between the grain orientation and the out-of-plane magnetic properties of nitrogen-enriched polycrystalline austenitic stainless steel surface is performed. Due to the competition between the magnetocrystalline anisotropy, the exchange and dipolar interactions, and the residual stresses induced by nitriding, the resulting effective magnetic easy-axis can lay along unusual directions. It is also demonstrated that, by choosing an appropriate stainless steel texturing, arrays of ferromagnetic structures with out-of-plane magnetization, embedded in a paramagnetic matrix, can be produced by local plasma nitriding through shadow masks. [ABSTRACT FROM AUTHOR]