Characterization of Minerals, Metals and Materials 2022: Advanced Microstructural Characterization Methods
Sponsored by: TMS Extraction and Processing Division, TMS: Materials Characterization Committee
Program Organizers: Mingming Zhang, Baowu Ouyeel Co. Ltd; Jian Li, CanmetMATERIALS; Bowen Li, Michigan Technological University; Sergio Monteiro, Instituto Militar de Engenharia; Shadia Ikhmayies; Yunus Kalay, Middle East Technical University; Jiann-Yang Hwang, Michigan Technological University; Juan Escobedo-Diaz, University of New South Wales; John Carpenter, Los Alamos National Laboratory; Andrew Brown, Devcom Arl Army Research Office; Rajiv Soman, Eurofins EAG Materials Science LLC; Zhiwei Peng, Central South University
Monday 2:00 PM
February 28, 2022
Room: 207B
Location: Anaheim Convention Center
Session Chair: John Carpenter, Los Alamos National Laboratory; Bowen Li, Michigan Technological University
2:00 PM Introductory Comments
2:05 PM
Challenges Concerning the Characterization of Cementite in Low Carbon Steel Using Electron Backscatter Diffraction: Mary O'Brien1; Kip Findley2; Samantha Lawrence1; 1Los Alamos National Laboratory; 2Colorado School of Mines
Understanding the location and morphology of cementite precipitation in steel has long been a challenge tackled almost exclusively with traditional transmission electron microscopy, particularly in low carbon steels. However, scanning electron beam techniques such as electron backscatter diffraction (EBSD) and transmission Kikuchi diffraction (TKD) can leverage automated diffraction pattern analysis and high scan rates to improve statistics in cementite analysis. Moreover, coupling energy dispersive spectroscopy (EDS) with simultaneous EBSD or TKD is desirable to assess alloy segregation to cementite. However, several challenges arise when utilizing these techniques including the large electron beam interaction volume, Hough indexing algorithms, and attributes of steel that make EDS interpretation challenging. This talk will discuss these challenges through the lens of a case study concerning low carbon microalloyed pipeline steel.
2:25 PM
Characterizing Microstructures of Additively Manufactured Nickel and Cobalt Based Superalloys via TriBeam Tomography: James Lamb1; McLean Echlin1; Tresa Pollock1; 1University of California Santa Barbara
Laser powder bed fusion (LPBF) is an additive manufacturing (AM) technique widely used within the aerospace and medical industries due to its ability to print complex geometries at low cost. However, the microstructure of these printed parts is highly variable both within a single print and across different print parameters. TriBeam tomography, a 3D characterization technique that incorporates a femtosecond pulsed laser with an FIB SEM for serial sectioning of mm3-scaled samples with sub-µm resolution, has particular utility for investigating the multiscale microstructural features that exist in AM material. In this work, a novel cobalt nickel superalloy printed via LPBF is reconstructed using the TriBeam, generating a large dataset in which orientation data, such as grain reference orientation deviation, and morphology data, such as grain size, is examined. Comparisons between the CoNi materials and 3D datasets collected from material printed with alternative AM methods and processing parameters will be discussed.
2:45 PM
Interpreting X-ray Absorption and Diffraction Contrast for Massive Non-destructive 3D Crystallographic Mapping of Metals in Laboratory CT: Andy Holwell1; Maadhav Kothari1; Hrishikesh Bale1; Jun Sun2; Jette Oddershede2; 1Carl Zeiss Microscopy Llc; 2Xnovo Technology ApS
Laboratory 3D X-ray microscopy (XRM) has previously been limited to imaging via material density differences within the sample. As such, single-phase polycrystalline materials (e.g. alloys) do not exhibit any absorption contrast to reveal the underlying grain microstructure. For microstructural crystallography, researchers have turned to time-consuming 3D electron backscatter diffraction in the scanning electron microscope in metallurgy, ceramics, semiconductors, pharmaceuticals, geology etc. Now, laboratory-based diffraction contrast tomography (DCT) can extract crystallographic information from single-phase polycrystalline samples, non-destructively and in three dimensions. DCT scans collect x-ray diffraction patterns which are deconvoluted for crystallographic reconstruction. Information on grain morphology, orientation, size and centroid position is available from the reconstructed 3D grain map, for studies of grain growth, tensile testing and aniostropy, delivering explicit grain structures for modeling. We show how LabDCT provides a routine solution for experimentally acquiring explicit 3D grain structures in various materials, enabling direct coupling of experimental results and simulations.
3:05 PM
Single Crystal Cast Microstructures Characterized by the RVB-EBSD Method: Pascal Thome1; Felicitas Scholz1; Jan Frenzel1; Gunther Eggeler1; 1Ruhr University Bochum
We present the Rotation Vector Base Line Electron Back Scatter Diffraction (RVB-EBSD) method, a new correlative orientation imaging method for scanning electron microscopy (OIM/SEM). The RVB-EBSD method was developed to study crystal mosaicity in as-cast Ni-base superalloy single crystals (SX). The technique allows to quantify small deviation angles (< 0.5°) between individual dendrites and to visualize the results in an intuitive way. The RVB-EBSD method is based on a cross correlation procedure. It applies Gaussian band pass filtering to improve the quality of more than 500 000 experimental patterns. A rotation vector approximation and a correction procedure, which relies on a base line function, are used. As an example we apply the method to compare two superalloy microstructures. We study competitive growth of dendrites after directional solidification in a Bridgman furnace. We compare the results with microstructures obtained from single crystalline Ni-base superalloys additively manufactured by selective electron beam melting.
3:25 PM Break
3:45 PM
A Multiscale, Multimodal Approach to Studying Static Recrystallization in Mg-3Zn-0.1Ca with In-situ nf-HEDM, ff-HEDM, and DFXM: Ashley Bucsek1; Sangwon Lee1; Reza Roumina1; Tracy Berman1; Can Yildirim2; Carsten Detlefs2; John Allison1; 1University of Michigan; 2European Synchrotron Radiation Facility
High-strength lightweight magnesium (Mg) alloys have substantial potential for lightweighting automobiles, aircraft, and other technologies, but compared to other structural metals, our understanding of Mg alloy physical metallurgy is less mature. In particular, the widespread use of Mg alloys requires significant improvement in formability, achievable through processing to weaken the texture. Here, we study a Mg-3Zn-0.1Ca alloy during annealing while taking in-situ measurements of the evolving microstructure using near-field and far-field high-energy diffraction microscopy (nf- and ff-HEDM) and dark-field X-ray microscopy (DFXM) on ID3A at CHESS and ID06 at the ESRF. By combining the different modalities, we were able to characterize the microstructure evolution during annealing across five orders of magnitude in length scale (10 nm to 1 mm), from the subgrain morphology of individual grains to the aggregate behavior of several thousands of grains, opening a direct window to the mesoscale processes during recovery, static recrystallization, and grain growth.
4:05 PM
Three-dimensional Atomic Mapping of Ligands on Nanoparticles by Atom Probe Tomography: Kyuseon Jang1; Seho Kim2; Hosun Jun1; Chanwon Jung1; Jiwon Yu3; Sangheon Lee3; Pyuck-pa Choi1; 1Korea Advanced Institute of Science and Technology (KAIST); 2Max-Planck-Institut für Eisenforschung GmbH; 3Ewha Womans University
Capping ligands are crucial to synthesizing colloidal nanoparticles with functional properties. However, the synergistic effect between different ligands and their distribution on crystallographic surfaces of nanoparticles during colloidal synthesis is still unclear despite powerful spectroscopic techniques, due to a lack of direct imaging techniques. In this study, atom probe tomography is adopted to investigate the three-dimensional atomic-scale distribution of two of the most common types of these ligands, cetrimonium (C19H42N) and halide (Br and Cl) ions, on Pd nanoparticles. The results, validated using density functional theory, demonstrate that the Br anions adsorbed on the nanoparticle surfaces promote the adsorption of the cetrimonium cations through electrostatic interactions, stabilizing the Pd {111} facets. In contrast, the Cl anions are not strongly adsorbed onto the Pd surfaces. The high density of adsorbed cetrimonium cations for Br anion additions results in the formation of multiple-twinned nanoparticles with superior oxidation resistance.