Advanced Characterization Techniques for Quantifying and Modeling Deformation: Session VII
Sponsored by: TMS Extraction and Processing Division, TMS Structural Materials Division, TMS: Advanced Characterization, Testing, and Simulation Committee, TMS: Materials Characterization Committee
Program Organizers: Arul Kumar Mariyappan, Los Alamos National Laboratory; Irene Beyerlein, University of California, Santa Barbara; Wolfgang Pantleon, Technical University of Denmark; C. Tasan, Massachusetts Institute of Technology; Olivia Underwood Jackson, Sandia National Laboratories

Thursday 8:30 AM
March 3, 2022
Room: 207A
Location: Anaheim Convention Center

Session Chair: Jay Carroll, Sandia National Laboratories; Mitra Taheri, Johns Hopkins University


8:30 AM  Invited
Accessing Order-dependent Defect Distributions Using Novel Diffraction Techniques: Mitra Taheri1; 1Johns Hopkins University
    Due to the inherent chemical disorder and the potential for tunable degrees of short-range order in these materials (SRO), the process of deformation substructure evolution in general, and slip-to-twin transition in particular, in medium entropy alloys (MEAs) is expected to deviate from that in conventional alloys. For FCC materials, after having previously developed a methodology for understanding deformation substructure formation in pure Cu, the group has turned its attention to the CoCrNi MEA system. In this talk, we relate processing parameters to the rise of SRO and ultimately to dynamic substructure development and mechanical behavior. Microstructures of HEAs subjected to a variety of deformation regimes and quantified using diffraction-based techniques. The extent to which SRO controls localized dislocation-based phenomena during microstructural evolution is discussed. The techniques presented allow for the direct observation of the interplay between chemistry and microstructure, and thus, provides us with key tuning knobs for future HEA development.

9:00 AM  
A Thermo-mechanical Model for Dislocation Dynamics in Transient Heterogeneous Temperature Fields: Manas Upadhyay1; 1LMS, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris
     A thermo-mechanical theory for dislocation dynamics, called the Thermal Field Dislocation Mechanics (T-FDM) model, has been recently proposed in Upadhyay JMPS 145 (2020) 104150. Its novelty lies in its capability to capture (i) dislocation transport, generation, annihilation and interactions with other defects under any thermo-mechanical loading (e.g., solid-state thermal cycling during AM, quenching, recovery, etc.), and (ii) local temperature changes due to dislocation dynamics.With the aim to perform simulations at experimental time scales while numerically maintaining “compact dislocation cores”, a time-explicit Runge-Kutta Discontinuous Galerkin Finite Element (RKDG-FE) implementation of the dislocation transport equation used in T-FDM has been proposed. For similar accuracy, simulations using this scheme are several orders of magnitude faster than those with existing FE implementation. Some results from dislocation transport/interaction simulations will be presented. The RKDG-FE scheme will facilitate a one-to-one comparison of the T-FDM model with advanced space/time-resolved characterisation techniques e.g., dark-field X-ray microscopy.

9:20 AM  
The Role of GNDs in Memory Response of FCC and BCC Metals during Deformation: Tristan Russell1; David Fullwood1; Robert Wagoner2; Sobhan Nazari Tiji2; Guowei Zhou3; 1Brigham Young University; 2Ohio State University; 3Shanghai Jiao Tong University
    Recent work suggests that many “memory” aspects of metal behavior such as Bauschinger effect and anelasticity, are consequences of internal stresses that develop as GNDs. In order to test this hypothesis, tensile experiments were performed with single crystal, bicrystal, and multicrystal samples of BCC Tantalum and FCC Nickel. DIC was also performed on the multicrystal samples using a gold remodeling technique to provide more data. The results of these tests were compared with predictive crystal plasticity simulations with and without the stress fields of GNDs accounted for. The results show that simulations with GNDs predict the form of anelasticity seeds in stress cycles, but underpredict the magnitude of the hysteresis. Identical simulations without GNDs predict essentially no hysteresis, 3 orders of magnitude smaller than observed. A tentative conclusion was reached: memory aspects arise from the internal stress from GNDs, but some aspects of their calculation are not fully understood.

9:40 AM  
Low kV EBSD & Physics-based Modeling of Dislocation Cell Structures in Aluminum: Toby Francis1; Chaoyi Zhu1; Elizabeth Holm1; Marc De Graef1; 1Carnegie Mellon University
    The evolution of dislocation cell structures lies at the center of many fundamental problems in additively manufactured metals, especially those involving recrystallization. The speed, resolution, and samples thickness accessible to modern electron backscatter diffraction (EBSD) holds the key to bridging the length-scales of the dislocation cell structure and the overall grain structure. However, imaging heavily deformed materials with high orientational accuracy within sub-grains at the resolution necessary to resolve the dislocation cell structure pushes the fundamental limits of EBSD. Combining advancements in physics-based modeling of EBSD with the sensitivity of direct electron detectors allows for imaging at lower accelerating voltages and increases the effective resolution of EBSD. Moreover, coupling an inverse model to the EBSD simulations can allow for the determination of the elastic strain field, crucial to recovery. These concepts are used to investigate the kinetics of recrystallization in aluminum using an in-situ heating rig.

10:00 AM Break

10:15 AM  Invited
Dominant Microstructural Features Impacting Failure in Additively Manufactured AlSi10Mg: Jay Carroll1; Christopher Laursen1; Philip Noell1; John Emery1; David Moore1; Garrett Pataky2; 1Sandia National Laboratories; 2Clemson University
    The behavior of additively manufactured (AM) materials is affected by many different microstructural characteristics such as grain structure, the distribution of alloying elements, and flaw population. Some of these characteristics are dominant over others in some circumstances depending on the loading scenario, the material, and the magnitude of the features among other variables. This work focuses on the effects of microstructural features on the structural properties and failure in AM alloy AlSi10Mg. Several experiments are presented that demonstrate the effects of various microstructural characteristics on strength, ductility, and fracture behavior. These interactions have been investigated through the analysis and alignment of several datasets from different experimental techniques. Measurements from scanning electron microscopy (SEM), X-Ray computed tomography (CT) and large numbers of high throughput tensile bars are compared. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.

10:45 AM  
Improving 2D Diffraction Peak Detection Using Shannon Entropy: Kieran Nehil-Puleo1; Jonthan Tischler2; Philip Eisenlohr1; 1Michigan State University; 2Argonne National Laboratory
    High-energy X-ray diffraction at synchrotron facilities frequently utilizes area detectors since the positions of diffraction peaks encode useful information about the illuminated crystal lattice. To pinpoint these locations, we propose a novel strategy that filters the raw (and typically noisy) intensity by calculating the Shannon entropy within a sliding window. The resulting image is thresholded at a value determined from the 90% and 95% intensity percentile. The intensity-weighted averaged positions of the resulting islands are then taken as the respective peak locations. We compare this modified strategy to the one presently established at beamline 34-ID-E (Advanced Photon Source) and found it to be more robust when the signal-to-noise ratio is low.

11:05 AM  
NOW ON-DEMAND ONLY – Exploring Plastic Deformation and Color of Metals with Mathematical Morphology: Michael Glazoff1; 1Idaho National Lboratory
    Mathematical morphology is employed for analysis and synthesis of plastic deformation and light scattering and diffraction in 2D and 3D. The well-established connection between surface topography, color, and visual brightness of deformed metals is explored to design “blue aluminum” via the effect of light scattering without diffraction (light traps). Other examples include a technique to evaluate the condition of a steel roll surface (important for rolling mill application), quantifying the effects of stretching, turning, and “orange peel” of deformed metallic surfaces. The proposed approach is nonlinear, multi-scale, general and, when used in conjunction with convolutional neural networks (CNNs), provides an interesting alternative/supplement to “deep learning”.

11:25 AM  
Use of Spherical Nanoindentation Protocols to Study the Anisotropic Mechanical Response of α-β Single Colonies in Ti-6Al-4V Alloy: Soumya Mohan1; Adam Pilchak2; Surya Kalidindi1; 1Georgia Institute of Technology; 2Air Force Research Laboratory
    The recently developed spherical nanoindentation stress-strain protocols were employed in this study to investigate systematically the anisotropic elastic and yield response of the α-β single colonies in a Ti-6Al-4V alloy. This was accomplished by indenting colonies with different lattice orientations of the α (measured by electron back-scattered diffraction) in the polycrystalline sample. The employed protocols were capable of providing reliable and consistent information on the anisotropy of the colonies in a high-throughput manner, compared to the other approaches being explored in the current literature. Furthermore, the responses measured in this study have been compared against similar measurements on differently oriented grains of primary α. It was noted that the α-β colonies exhibit distinctly different elastic and plastic anisotropy compared to the primary α grains. A dip in the indentation yield properties at 45 degrees declination angle is observed, and a lack of anisotropy is observed in the elastic properties.

11:45 AM  
Advanced Characterization of Mock High Explosive: Summer Camerlo1; William Wallace1; Gus Becker1; Amy Clarke1; Kester Clarke1; 1Colorado School of Mines
    Potential safety concerns drive interest in the development and use of mock high explosive (HE) surrogates that emulate aspects of high explosives. In particular, the processing and thermo-mechanical behavior of compacted pristine and recycled mock HE is studied to further multiscale modeling of mock HE response with exascale computing. In this presentation, we report on recent experimental efforts at the Colorado School of Mines to process mock HE samples and other particle/matrix assemblies, and perform characterization with x-ray computed tomography (CT) and compression testing; including testing at 100 s-1 that is challenging experimentally but was successful. In-situ x-ray CT during quasi-static deformation is also pursued to understand particulate/matrix assembly response under load. The aim is to generate three-dimensional information about particle sizes, morphologies, distributions and thermo-mechanical response to inform modeling of problems involving granular flows, large deformations, and fracture/fragmentation of unbonded and bonded particulate materials, emphasizing mock HE.