5th International Congress on 3D Materials Science (3DMS 2021): Materials Dynamics in 3D
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
Tuesday 9:50 AM
June 29, 2021
Room: Virtual C
Location: Virtual
Session Chair: Henning Friis Poulsen, Technical University of Denmark
3D Mapping of Type-III Stress in Plastically Deformed Steel: Yujiro Hayashi1; 1RIKEN SPring-8 Center
Materials modeling for the prediction of mechanical behavior of alloys requires advances in multiscale 3D measurement of stress and its evolution produced by mechanical events. We show non-destructive 3D mapping of intragranular local (type-III) stress in plastically deformed multiple grains embedded in mm-sized bulk steel using scanning 3DXRD. The grains were illuminated by a high-energy X-ray microbeam from various directions. Non-overlapped multiple diffraction spots per grain were detected through a conical slit. Type-III elastic strain tensors under 5% plastic deformation were determined from the differences between observed scattering angles and stress-free Bragg angles. The observed type-III stress deviated by a value as high as the yield strength from grain-averaged (type-II) stress. The type-III stress was in a triaxial stress state even under elongation smaller than the uniform elongation. Multiscale modeling of deformation and failure of steel will be facilitated using the non-destructive 3D type-III stress tensor mapping data.
4D Characterization of Solidification in Al-based Droplets: Jonas Valloton1; Abdoul-Aziz Bogno1; Christian Schlepütz2; Guillaume Reinhart3; Michel Rappaz4; Hani Henein1; 1University of Alberta; 2Paul Scherrer Institut; 3Aix-Marseille Université; 4Ecole Polytechnique Fédérale de Lausanne
Sub-millimeter droplets of near eutectic Al-Cu alloy were melted and solidified using the laser-based heating system available at the TOMCAT beamline of the Swiss Light Source. Cooling rates were monitored using a thermocouple placed at the base of the crucible. During cooling, radiography scans at 1 kHz frame rate were acquired in order to capture the solidification front in-situ. The corresponding field of view allowed the scanning of two droplets at once while providing sufficient resolution to observe the envelope of the solidification front (0.81 μm pixel size). Micro-tomography scans with a pixel size of 0.325 μm were then performed on the solidified samples to analyze the microstructure. Primary dendrites of either α-Al or Al2Cu were observed, followed by a eutectic front. The low growth velocities measured by radiography (100-10-1 mm/s) suggests low undercoolings. Surprisingly, a deviation from the typical <100> growth direction has been observed for primary Al dendrites.
Characterization of Free-growing Dendrites Using 4D X-ray Tomography and Machine Learning: Tiberiu Stan1; Kate Elder1; Xianghui Xiao2; Peter Voorhees1; 1Northwestern University; 2Brookhaven National Laboratory
When metallic alloys are cooled from the liquid, in almost all cases from castings to additive manufacturing, the metal freezes via the formation of dendrites. Using high temporal and spatial resolution synchrotron 4D x-ray computed tomography (XCT), we present the first in-situ observations of free-growing “hyperbranched” dendrites in Al-Zn. Convolutional neural networks were used to segment the reconstructed datasets, and interface energy anisotropy calculations combined with XCT morphological observations were used to track the crystallographic growth directions of dendrite tips through time. We show that a single dendritic root can have arms with tip morphologies ranging from nearly spherical to highly elliptical. Dendrite fragments are also observed moving both with and against gravity, indicating density changes during growth. The 4D experiments give new information regarding the evolution of dendrite tip curvatures, velocities, crystallography, symmetries, and the interface energy anisotropies of Al alloys.
Dark Field X-ray Microscopy of Recovery Annealing of Cold Rolled Fe-Si and Fe-Si-Sn Alloys: Can Yildirim1; Nikolas Mavrikakis2; Melanie Gauvin2; Phillip Cook3; Mustafacan Kutsal4; Roger Hubertt2; Wahib Saikaly2; Henning Poulsen5; Myriam Dumont6; Helena Zapolsky7; Dominique Mangelick8; Carsten Detlefs4; 1CEA Grenoble; 2OCAS; 3BOCU; 4European Synchrotron Radiation Facility; 5DTU; 6Universite Aix Marseille; 7Universite De Rouen; 8IM2NP
Numerous interesting phenomena occur at different microscopic scales during the annealing of engineering materials. Understanding these phenomena are essential not only for optimising performance of macroscale components, but also for the validation of structural models. Here, we present an in-situ study on the effect of Sn on the recovery annealing of cold rolled Fe-3%Si alloys using Dark Field X-ray Microscopy. DFXM is a recent non-destructive, diffraction-based technique that allows 3D mapping of orientation and lattice strain with 100 nm spatial and 0.001° angular resolution within embedded in bulk samples. The evolution of relative strain and orientation in alpha Fe grains upon annealing show that Sn slows down the recovery kinetics. DFXM results provide a direct observation of the strain field around dislocation loops that remain static upon annealing.These findings agree with the complementary micro-hardness and EBSD measurements. We further discuss this by an atomistic modelling on Sn-dislocation interaction.
Microstructural Stability of a Three-phase Eutectic Examined via 4D X-ray Nano-tomography: George Lindemann1; Viktor Nikitin2; Vincent De Andrade2; Marc De Graef3; Ashwin Shahani1; 1University of Michigan; 2Argonne National Laboratory; 3Carnegie Mellon University
Multiphase materials often operate at elevated temperatures where coarsening may cause significant microstructural changes. Therefore, a thorough understanding of coarsening mechanisms in such materials is critical to accurately predict their behavior in-service. Here, we use 4D x-ray nano-tomography (three spatial dimensions and time) to investigate microstructure evolution of an Al-Ag2Al-Al2Cu three-phase eutectic alloy during isothermal annealing below the eutectic temperature. With the aid of a new, in situ furnace and an innovative total variation regularization reconstruction technique, we visualize the evolution of eutectic lamellae and identify two unique coarsening modes that occur in parallel for the two intermetallic phases. Ag2Al coarsens via 2D Ostwald ripening when the rod’s initial radius is greater than a critical value while Al2Cu evolves via 3D Ostwald ripening. We also consider the role of crystallographic anisotropy. Our efforts reveal the need to expand contemporary theories of eutectic coarsening to better describe multiphase and multicomponent systems.
Observation of Plastic Slip Localization in a Ti-7Al Alloy Using X-ray Topotomography: Patrick Callahan1; Jean-Charles Stinville2; McLean Echlin2; Wolfgang Ludwig3; Henry Proudhon4; Tresa Pollock2; 1Naval Research Laboratory; 2University of California, Santa Barbara; 3ESRF - European Synchrotron Radiation Facility; 4MINES ParisTech, PSL Research University, MAT-Centre des Materiaux, CNRS
Specimens of the titanium alloy Ti-7Al were studied with high-resolution digital image correlation (HR-DIC) in an SEM along with x-ray diffraction contrast tomography (DCT) and x-ray topotomography (TT) at a synchrotron facility. Several of the samples were pre-strained near the elastoplastic transition before DCT and TT was performed. This enabled regions of localized plasticity, or slip localization, observed in 3D within both bulk and surface grains using TT to be correlated with HR-DIC observations of plasticity at the surface. In another sample, a number grains of interest were identified prior to deformation using DCT. TT data was collected from these grains before deformation, and then at several deformation steps in order to study the evolution of slip localization in 3D. These observations can provide new insights into plastic localization as it relates to microstructural configurations and on plastic transmission between grains both at the surface and internally in 3D.
The Effect of 3D Microstructure on Deformation-induced Martensitic Transformation in Austenitic Fe-Cr-Ni Alloys: Ye Tian1; Ming Guan1; He Liu2; Robert Suter2; Peter Kenesei3; Jun-Sang Park3; Todd Hufnagel1; 1Johns Hopkins University; 2Carnegie Mellon University; 3Argonne National Laboratory
Deformation-induced transformation of individual grains in Fe-Cr-Ni alloys from austenite (fcc) to α'-martensite (bcc) is strongly influenced by the local stress state, which in turn is a function of the local microstructure. To investigate these effects, we have performed near-field and far-field high-energy diffraction microscopy (HEDM) to characterize the deformation-induced martensitic transformation in high-purity Fe-Cr-Ni alloys during in situ tensile loading. For the range of Fe-Cr-Ni alloys studied, martensite start () temperatures are close to room temperature, where both stress-assisted and strain-induced formation of martensite are possible during deformation. Three-dimensional (3D) in situ reconstructions were performed including austenitic substrate and newly formed α'-martensite. Both the strain tensor evolution and neighboring environment of individual austenite grains were tracked during the loading, and correlated with martensite formation. We discuss the transformation mechanism discussed in light of the stacking-fault energy of the alloys and the grain-averaged stress state.
Time Evolution of Dislocations and Defects with Dark-field X-ray Microscopy: Leora Dresselhaus-Cooper1; Suzanne Ali1; Sean Breckling2; Philip Cook3; Carsten Detlefs4; Jon Eggert1; Eric Galtier5; Lisseth Gavilan-Marin6; Arnulfo Gonzalez2; Marylesa Howard7; Kento Katagiri8; Hyunjung Kim9; Sangsoo Kim10; Sunam Kim10; Sungwon Kim9; Sungwook Kim9; Stephan Kuschel5; Hae Ja Lee5; Chuanlong Lin11; R. McWilliams12; Daewoong Nam10; Norimasa Ozaki8; Ricardo Pedro13; Henning Poulsen14; Alison Saunders1; Frank Schoofs14; Toshimori Sekine15; Hugh Simons14; Bihan Wang11; Wenge Yang11; Grethe Winthers14; Can Yildirim16; 1Lawrence Livermore National Laboratory; 2Nevada National Security Site; 3BOKU; 4ESRF; 5SLAC National Accelerator Laboratory; 6NASA Ames; 7 Nevada National Security Site; 8Osaka University; 9Sogang University; 10Pohang Accelerator Laboratory; 11HPSTAR; 12University of Edinburgh; 13Massachusetts Institute of Technology; 14Technical University of Denmark; 15U.K. Atomic Energy Authority; 16CEA
A material’s response to its surroundings depends on both its native properties and the imperfections (defects) in its structure. While techniques exist to probe material defects, they are mainly limited to surface measurements or rastered scans that cannot measure the dynamics of irreversible processes. Dark-field X-ray microscopy (DFXM) can now directly image defects in single- and poly-crystals, resolving the lattice tilt and inclination with high sensitivity over long length-scales. We have extended DFXM to synchrotron and X-ray free electron laser experiments to directly image the time evolution of defects in materials—focusing on defects at the mesoscale (e.g. dislocations). These movies resolve the dynamics of defects in single crystals, directly measuring their mobility and interactions by measuring the strain with 10-5 resolution over hundreds of micrometers. With this new tool, I demonstrate how dislocations evolve in aluminum during annealing, and how cumulative radiation damage evolves. Time-resolved DFXM holds important opportunities for future studies on mesoscale dynamics, as it can inform models that have previously been refined only by indirect measurements and multi-scale models.
Towards Quantitative Modeling of Precipitate Morphology Evolution in Co-based Superalloys: Wenkun Wu1; James Warren2; Peter Voorhees3; Olle Heinonen4; 1Center for Hierarchical Materials Design (CHiMaD), Northwestern University; 2Materials Measurement Laboratory, National Institute of Science and Technology; 3CHiMaD, Northwestern University; Department of Materials Science and Engineering, Northwestern University; 4Materials Science Division, Argonne National Laboratory
Cobalt-based superalloys with γ/γ' microstructures offer great promise as candidates for next-generation high-temperature alloys. It is essential to understand the thermodynamic and kinetic factors that influence the microstructural evolution of these alloys in order to optimize the alloy compositions and processing steps with a goal to improve their coarsening, creep and rafting behavior. We are developing a phase field approach using the chemical free energies extracted from CALPHAD thermodynamic data developed at NIST to predict the equilibrium shapes of Co-Al-W γ' precipitates. We find that the equilibrium shape of the precipitate results from a delicate competition between chemical, interfacial and elastic energies. We are examining how modeling input parameters such as the form of the chemical free energy, anisotropy of the interfacial energy, and variant misfit and diffusivity due to temperature change affect the coarsening and rafting behavior of superalloy models and relate these parameters to experimentally available values.