5th International Congress on 3D Materials Science (3DMS 2021): Characterization Methods II
Program Organizers: Dorte Juul Jensen, Technical University of Denmark; Erica Lilleodden, Fraunhofer Insitute for Microstructure of Materials and Systems (IMWS); Scott Barnett, Northwestern University; Keith Knipling, Naval Research Laboratory; Matthew Miller, Cornell University; Akira Taniyama, The Japan Institute of Metals and Materials; Hiroyuki Toda, Kyushu University; Lei Zhang, Chinese Academy of Sciences
Wednesday 12:10 PM
June 30, 2021
Room: Virtual B
Location: Virtual
Session Chair: Erica Lilleodden, Fraunhofer Insitute for Microstructure of Materials and Systems (IMWS)
3D Maps of Geometrically Necessary Dislocation Densities in Polycrystalline IN718: Wyatt Witzen1; Andrew Polonsky1; Tresa Pollock1; Irene Beyerlein1; 1University of California, Santa Barbara
Three dimensional Electron Backscatter Diffraction (3D EBSD) as a method oforientation analysis offers the ability to characterize material microstructure in 3D space, allowing the calculation of Geometrically Necessary Dislocation (GND) densities. Feature reference misorientation within each grain imaged in this dataset reveals that some grains exceed 20 degrees in misorientation to the overall orientation of the grain, leading to the partitioning of subgrains and other areas of high misorientation within single grains. This orientation imaging technique allows GND density mapping in 3D space and provides insight to these subgrain features, particularly useful for additively manufactured material characterization. In this study, GND densities ranging from roughly 1× 1011 to 1.8 × 1013 m-2 have been calculated from the high degree of misorientation within these grains. Additionally, GNDs are calculated using different nearest-neighbor environments to understand how disorientation measured over different neighborhood configurations will influence the GND densities calculated.
3D Non-destructive Characterization of Texture Evolution in Electrical Steels with Laboratory Diffraction Contrast Tomography: Jun Sun1; Florian Bachmann1; Jette Oddershede1; Erik Lauridsen1; 1Xnovo Technology
Electrical steels with high silicon contents are widely used in electrical power transformers, motors and generators. Texture is the most important property for electrical steel as the orientations of grains have strong influences on the magnetization and electrical resistance of the materials. Laboratory diffraction contrast tomography (LabDCT) is a recently developed X-ray based technique that is able to map the grain morphology and crystallographic orientation non-destructively in 3D. The capability of LabDCT in analyzing the grain structure in electrical steel with significant statistics brings unprecedented insights into the research of electrical steels. In this work, we will present the results of using LabDCT to characterize both non-oriented and oriented electrical steels, with discussion on how this non-destructive 3D technique will contribute to the study of dynamic texture development in electrical steels.
Cancelled
Analysis of Deformation Modes of AZ31 Magnesium Alloys Using EBSD and DCT: Jaehyung Cho1; Sang Ho Han1; Geon Young Lee1; Jun-Ho Lee1; Jun Sun2; 1Korea Institute of Materials Science; 2Xnovo Technology ApS
Various activation of deformation modes of AZ31 magnesium alloys during plane strain compression can be experimentally investigated using electron backscatter diffraction (EBSD) and XRD diffraction contrast tomography (DCT). Activity of the major deformation modes of basal and non-basal slips and twinning during deformation are examined and compared with prediction by crystal plasticity. Three-dimensional microstructural features can be obtained using diffraction contrast tomography. In particular, laboratory diffraction contrast tomography (LabDCT) makes use of high-resolution diffraction images acquired on a ZEISS Xradia Versa X-ray microscope. The capabilities of LabDCT to include full reconstruction of the 3D grain structure including both grain morphology and crystallographic orientation, makes it possible to analyse in detail of structural heterogeneities and texture present in the sample. Effect of spatial distribution and grain boundary character of grain orientations on activity of deformation modes are discussed.
Combined Strain Measurements and 3D Tomography in Inconel 718: Marie Charpagne1; Jean-Charles Stinville1; Toby Francis1; Andrew Polonsky1; McLean Echlin1; Patrick Callahan2; Valery Valle3; Tresa Pollock1; 1University of California, Santa Barbara; 2Naval Research Laboratory; 3Universite de Poitiers
Damage during mechanical loading of polycrystalline metallic alloys involves plastic strain localization at the scale of individual grains. The development of predictive models for monotonic and cyclic loading requires quantitative assessment of these processes at the sub-micron scale. This study aims at understanding strain localization processes in relation to the 3D microstructure in the structural alloy Inconel 718, by combining Digital Image Correlation data acquired in a Scanning Electron Microscope with 3D EBSD data. The use of discontinuity tolerant DIC codes enables to resolve the individual components at each slip band, which when coupled to crystallographic data, enables to determine the active slip system. To do so, multi-modal data merging techniques have been employed to recombine the strain localization information with the 3D grain structure and crystallographic orientations, acquired using TriBeam tomography. Quantitative correlations between microstructure features (grain boundaries, twin boundaries, triple junctions, quadruple points, etc.) will be discussed.
Equations for Grain Boundary Motion in Finite-element Simulations: Erdem Eren1; Jeremy Mason1; 1University of California, Davis
Simulating microstructure evolution on a finite element mesh is challenging; some existing formulations do not allow for anisotropic grain boundary properties, have unphysical anisotropy from the underlying numerical model, or allow only a restricted set of topological events that bias the grain boundary network evolution. Our group has been developing a FEM simulation that (1) uses a volumetric mesh to allow the inclusion of arbitrary material physics, (2) significantly expands the set of topological events to allow for general grain boundary network dynamics, and (3) proposes an energy dissipation criterion to identify the physically most plausible of these events. The performance of three proposed equations of motion for grain boundaries is evaluated and compared to known analytical results. The resulting code is expected to improve our ability to use recently-available experimental observations of three-dimensional microstructure evolution to develop predictive simulations.
Large-volume 3D EBSD System and Its Application to the Investigation of Grain Boundary Corrosion in 316L Stainless Steel: Shao-Pu Tsai1; Peter J. Konijnenberg2; Ivan Gonzalez1; Samuel Hartke1; Thomas A. Griffiths1; Stefan Zaefferer1; Akira Taniyama3; Kaori Kawano-Miyata3; 1Max-Planck-Institut für Eisenforschung GmbH; 2Bruker Nano GmbH; 3Research and Development, Nippon Steel Corporation
A large-volume 3D EBSD system consisting of an SEM (Zeiss crossbeam XB 1540) with a dedicated sample docking station, an adapted mechanical polishing automaton (ATM X-Change), and a collaborative robotic arm (Universal Robots UR5) has been assembled. An in-house designed software orchestrates the whole automation process via a communication hub. To obtain accurate serial sections of constant thickness, the polishing parameters (e.g., force exerted on the polishing cloths) were fine-tuned in a large number of preliminary tests on the material of interest. All samples were featured with top-observable side markers for polishing depth measurement. These markers were produced by plasma focused ion beam (PFIB). 3D EBSD data sets with a total volume of 300 × 300 × 300 µm³ reconstructed from approx. 100 slices were acquired to study the grain boundary corrosion behavior of 316L stainless steel. Corrosion tests were applied on the remaining bulk surface.
Optimizing Laboratory X-ray Diffraction Contrast Tomography for Characterization of the Grain Structure in Pure Iron: Adam Lindkvist1; Haixing Fang1; Dorte Juul Jensen1; Yubin Zhang1; 1Technical University of Denmark
Laboratory diffraction contrast tomography (LabDCT) is a recently developed technique for 3D non-destructive grain mapping using laboratory X-rays. The aim of the present work is to quantify the effects of the experimental parameters on the characterization of the 3D grain structure in iron. The experimental parameters studied include accelerating voltage, exposure time, as well as the number of projections. The quality of the grain reconstruction as a function of these parameters is evaluated by comparing the experimental and simulated diffraction patterns. Based on such evaluation, optimized experimental parameters are obtained for the 3D reconstruction of grains with certain sizes. The results of this optimization will be presented, and possible ways to extend the limits of the LabDCT technique will be discussed.
The Isothermal Evolution of Nanoporous Gold (npg) from the Ring Perspective: Markus Ziehmer1; Erica Lilleodden1; 1Helmholtz-Zentrum Geesthacht
The interconnected ligament network of npg may be seen as put together by torus-like rings. Similar to the reduction of the number of structural elements in other coarsening phenomena, npg reduces its number of rings during coarsening. Two basic mechanisms appear conceivable, ring collapse and ligament pinch-offs, both being fundamentally different topological transitions. To better understand this aspect of npg microstructure evolution, isothermally annealed samples were decomposed into their relevant rings, applying results and algorithms from graph theory to skeletonized 3D reconstructions from focused ion beam tomography. This approach enabled to analyze distributions of topological classes, referring to number of ring edges, and their evolution over isothermal annealing. The results from five samples show a broadening of these distributions, suggesting an increasing relative dominance of pinch-offs over time. One consequence is a slow but steady increase of the average number of ring edges, that speaks against a self-similar evolution.