AFRL Additive Manufacturing Modeling Series: Challenge 4, 3D Reconstruction of an IN625 High-Energy Diffraction Microscopy Sample Using Multi-modal Serial Sectioning

Abstract

High-energy diffraction microscopy (HEDM) in-situ mechanical testing experiments offer unique insight into the evolving deformation state within polycrystalline materials. These experiments rely on a sophisticated analysis of the diffraction data to instantiate a 3D reconstruction of grains and other microstructural features associated with the test volume. For microstructures of engineering alloys that are highly twinned and contain numerous features around the estimated spatial resolution of HEDM reconstructions, the accuracy of the reconstructed microstructure is not known. In this study, we address this uncertainty by characterizing the same HEDM sample volume using destructive serial sectioning (SS) that has higher spatial resolution. The SS experiment was performed on an Inconel 625 alloy sample that had undergone HEDM in-situ mechanical testing to a small amount of plastic strain (~ 0.7%), which was part of the Air Force Research Laboratory Additive Manufacturing (AM) Modeling Series. A custom-built automated multi-modal SS system was used to characterize the entire test volume, with a spatial resolution of approximately 1 µm. Epi-illumination optical microscopy images, backscattered electron images, and electron backscattered diffraction maps were collected on every section. All three data modes were utilized and custom data fusion protocols were developed for 3D reconstruction of the test volume. The grain data were homogenized and downsampled to 2 µm as input for Challenge 4 of the AM Modeling Series, which is available at the Materials Data Facility repository.

Q-RBSA: High-Resolution 3D EBSD Map Generation Using An Efficient Quaternion Transformer Network

“…When considering data beyond the use-case sets tested, the approach shown here is directly applicable to any serial sectioning technique for gathering 3D EBSD information, including FIB sectioning, laser ablation, and robotic serial sectioning [7,6]. Further, data from other 3D grain mapping techniques that rely on synchrotron X-ray sources such as diffraction contrast tomography (DCT) [5] or high energy diffraction microscopy (HEDM) [4,3] may also be applicable for the infrastructure presented here.…”

“…To collect crystallographic microstructure information, 3D microscopy techniques have been developed that span lengthscales from nanoscale to mesoscale [2]. These experiments require costly or challenging to access equipment, like synchrotron light sources for high X-ray fluxes [3,4,5], precise automated robotic mechanical polishing and imaging [6,7], or high-energy ion beams and/or short pulse lasers coupled to electron microscopes [8,9]. Recent advancements in 3D experimentation have greatly reduced the time required for other aspects of data collection, but serial sectioning methods (where material is progressively removed from the sample between images) predominately rely on electron backscatter diffraction (EBSD) imaging for collecting crystallographic information, which is three orders of magnitude slower per pixel (ms per pixel) than standard secondary electron or backscatter electron imaging (µs per pixel).…”

Recent Developments in Femtosecond Laser-Enabled TriBeam Systems

“…However, to use automation to statistically assess these datasets, multimodal data fusion must be performed with accurate spatial data merging. Data fusion is challenging due to the need for identifiable reference features to merge the data modalities, 23,71,103,104 and due to the nonuniform imaging distortions that are inherently present with all detectors and scanning-based measurement mappings. [105][106][107] Nevertheless, a number of algorithms have been developed to solve the data fusion problem.…”

“…[105][106][107] Nevertheless, a number of algorithms have been developed to solve the data fusion problem. For example, TriBeam data and synchrotron x-ray DCT data have been fused to study grain growth evolution in strontium titanate, 68,108 mechanical serial sectioning and nearfield x-ray HEDM information in a superalloy, 23 strain measurements by SEM-based digital image correlation (DIC) have been fused with TriBeam data to understand slip in superalloys, 86 and pore locations have been fused with TriBeam grain orientation information in tantalum 85 and an AM superalloy 70 to understand the processing routes and damage accumulation.…”

“…19,20 Serial sectioning is a process by which material is removed layer by layer, such that at each slice the surface can be imaged. Briefly, the sectioning step for material removal may employ methods such as mechanical polishing, [21][22][23] ultramicrotomes for soft materials and metals, 24,25 broad argon-ion beams (BIBs), 26,27 plasma focused ion beams (PFIBs), 28,29 gallium focused ion beams (FIBs), 30,31 and the focus of this article-lasers.…”