Advanced Characterization Techniques for Quantifying and Modeling Deformation: Session III
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 Jackson, Sandia National Laboratories

Tuesday 8:00 AM
March 21, 2023
Room: Aqua 311A
Location: Hilton

Session Chair: Dalton Shadle, Cornell University; Ramamurty Upadrasta, Nanyang Technological University


8:00 AM  Invited
Size Effects and Failure Regimes in Notched Micro-cantilever Beam Fracture: Devashish Rajpoot1; Parag Tandaiya1; R Lakshmi Narayan2; Ramamurty Upadrasta3; 1IIT-Bombay; 2IIT-Delhi; 3Nanyang Technological University
    Fracture tests using notched micro-cantilever (MC) specimens are increasingly being used to measure the fracture toughness of materials at the micro-scale. Finite element analyses (FEAs) of loading of self-similar micro- and bulk cantilever beam fracture specimens using isotropic, elastoplastic constitutive models, are conducted to critically examine the validity of the toughness data obtained using MC specimens. A transition in the failure regimes from crack propagation to plastic collapse of the uncracked notch ligament is identified. While the crack propagation regime allows for the estimation of valid fracture toughness of the probed material, the plastic collapse regime does not. The effects of specimen aspect ratios, material hardening, and yield criteria on the master curves and transition point are examined and a method to interpret the failure regimes, assess the validity and size effects in micro-cantilever fracture tests on bulk metallic glasses, nano-crystalline materials and ultra-fine grained materials is proposed.

8:30 AM  
Kink Band Formation in Nano Metallic Laminates: Yifan Zhang1; Rodney McCabe1; Miroslav Zecevic1; Thomas Nizolek1; Nan Li1; Ricardo Lebensohn1; John Carpenter1; Laurent Capolungo1; 1Los Alamos National Laboratory
    Kink band (KB) formation is a common but not-well understood failure mechanism in anisotropic materials such as nano-metallic laminates (NMLs). In this work, we utilize in situ micro pillar compression in a SEM. S/TEM and transmission Kikuchi diffraction (TKD) microstructure analyses provide detailed microstructure characterization before and after kink band formation. We study the effects of layer thickness, layer waviness, interfaces, material system, and annealing on KB formation in Al/Fe, Ag/Fe and Cu/Fe NMLs prepared by accumulative roll bonding (ARB). The probability of observing kink banding decreases and the initiation strain for kink banding increases with increased layer thickness, decreased waviness amplitude, annealing, and decreased interface barrier strength to dislocation transmission. Furthermore, the experiments are simulated using a strain-gradient crystal plasticity model based on fast Fourier transforms, and good agreement is observed, which allow us to rationalize the microscopic mechanisms controlled by dislocation/interface interactions, leading to KB formation.

8:50 AM  
Understanding Deformation Behavior in an Al Alloy via Multimodal 3D Characterization: Andrew Polonsky1; Philip Noell1; Julia Deitz1; Hojun Lim1; John Emery1; Kyle Johnson1; 1Sandia National Laboratories
    Microstructure evolution during plastic deformation is a complex phenomenon controlled by myriad processes. Multimodal characterization approaches can provide the high-fidelity data required to make accurate predictive models of material response. In this work, we present 3D characterization of a wrought sample of Al 2219 both before and after macroscopic deformation. By combining non-destructive methods like diffraction contrast tomography (DCT) with serial sectioning within an electron microscope using the TriBeam system, 3D reconstructions of grain structure and orientation can be captured at multiple stages of the deformation process, providing insight into microstructural evolution and damage accumulation in a wrought Al alloy. Details of the reconstruction process and the opportunities for multimodal data fusion will be presented. The application of these data to crystal plasticity modeling will also be discussed.

9:10 AM  
In Situ Thermomechanical Loading of Nanocrystalline Alloys: Thomas Koenig1; Hongyu Wang2; Yong Zhu2; Ankit Gupta3; Alicia Koenig1; Garritt Tucker3; Gregory Thompson1; 1University of Alabama; 2North Carolina State University; 3Colorado School of Mines
    Nanocrystalline (NC) Ni-40Cu and Ni-40Cu-0.6P (at.%) alloys were mechanically loaded in tension at ambient (22 °C) and elevated (150 °C) temperatures with the deformed nanostructure captured by in situ transmission electron microscopy. The thermomechanical loading was provided by a custom microelectromechanical system (MEMS) shuttle structure. While mechanical strength softening was observed in both alloys upon thermomechanical heating, the fracture strength of the ternary alloy was higher than its binary counterpart regardless of temperature with intergranular failure observed as the failure mechanism. In the binary alloy, a coarse-toothed fracture profile was noted before failure compared to a fine-toothed fracture profile observed in the ternary alloy. Collectively, these differences were linked to P within the grain boundaries through atomistic simulations. Digital image correlation (DIC) was employed and is discussed for in situ image data mining, with the current limitations of the technique considered for both crystalline and non-crystalline materials.

9:30 AM Break

9:50 AM  
Characterization of the Impact of Grain-Neighborhoods on Cyclic Twinning in Magnesium Alloys Using High Energy X-Ray Diffraction: Duncan Greeley1; Mohammadreza Yaghoobi1; Katherine Shanks2; Darren Pagan2; Veera Sundararaghavan1; John Allison1; 1University of Michigan; 2Cornell High Energy Synchrotron Source
    Twinning and detwinning are a primary concern for cyclic deformation in magnesium alloys, and accurately modelling grain-scale cyclic mechanical response requires a more detailed understanding of the role of grain neighborhoods on deformation twin activity. In this study, we have developed an automated reconstruction procedure for identifying and tracking 3D grain-resolved twin evolution in magnesium alloys using combined far-field and near-field High Energy X-Ray Diffraction Microscopy (HEDM). Twinning and detwinning were characterized using this reconstruction procedure in pure magnesium, Mg-4wt.%Al, Mg-7.5wt.%Y, and Mg-2.4wt.%Nd during single cycle compression-tension displacements experiments at the Cornell High Energy Synchrotron Source (CHESS). The impact of grain local neighborhood texture and stress states on the evolution of cyclic twinning and detwinning and the role of binary alloying and grain size on twin activity were investigated, and the grain-scale cyclic mechanical response in the reconstructed microstructures were modelled using crystal plasticity finite element methods.

10:10 AM  
Effect of Strain Rate on Slip Activation in a Mg-Al alloy by In-situ 3DXRD: Gaoming Zhu1; Anatoly Shabalin1; Ulrich Lienert1; Leyun Wang2; 1Deutsches Elektronen-Synchrotron (DESY); 2Shanghai Jiao Tong University
    Strain rate sensitivity (SRS) plays a significant role on the plastic deformation of metals. In general, different slip systems exhibit their own SRS during deformation, especially for low-symmetry HCP alloys. However, the effect of SRS on slip systems still remains elusive and requires detailed consideration. Based on three-dimensional X-ray diffraction (3DXRD) method, three in-situ tensile experiments were carried out on a Mg-3 wt.%Al alloy at beamline P21.2 at PETRA III, DESY, with various strain rates of 1×10-2, 1×10-3, and 1×10-4. By self-developed scripts, grain rotation, stress evolution, and diffraction spot broadening of hundreds of grains for each sample can be tracked up to 4% strain. In this presentation, we will introduce: (i) how to obtain critical resolved shear stress (CRSS) values of different slip systems by diffraction spot broadening and grain rotation; (ii) how SRS affects the CRSS and work hardening behavior of different slip systems.

10:30 AM  
Measurement and Modeling of Grain Scale Tensorial Stresses in Notched Zirconium Specimens: 3D-XRD vs CPFE: Karim Louca1; Katherine Shanks2; Darren Pagan2; Hamidreza Abdolvand2; 1University of Western Ontario; 2Cornell High Energy Synchrotron Source (CHESS)
    Understanding the impacts of cracks and notches on material behaviour in ductile alloys is crucial for developing macro- and microscale predictive models. The impact of microstructure near flawed geometries can be significant to the material’s fatigue behaviour, specially in hexagonal close-packed (HCP) crystals with a high degree of elastic and plastic anisotropy. In this study, three-dimensional synchrotron X-ray diffraction (3D-XRD) is employed to investigate the effects of different notches on the grain-resolved tensorial stresses near the notch tips in pure zirconium specimens. The “as-measured” microstructures and notch geometries are subsequently imported into a crystal plasticity finite element (CPFE) model to simulate the evolution of stress, strain, and rotation fields. Results show that load sharing between different grain orientations contributes significantly to the stress development in the vicinity of notches. As a result, grains with similar orientations undergo different plastic strain rates, depending on their positions with respect to the notch.

10:50 AM  Invited
Extending High Energy Diffraction Microscopy to Track Localized Deformation with an Intragranular Signature during Cyclic Loading: Dalton Shadle1; Kelly Nygren2; Matthew Miller1; 1Cornell University; 2Cornell High Energy Synchrotron Source
    Localized deformation in a ductile, polycrystalline metal subjected to cyclic loading can be a life-limiting mechanism leading to fatigue crack initiation. Current in-situ characterizations, like in-situ high energy diffraction microscopy (HEDM), observe certain aspects of individual grains as they evolve due to localized deformation, but fall short of characterizing the polycrystal everywhere, all the time, at all resolutions. While in-situ HEDM “peers” within a material throughout evolution of the polycrystal, it fails to directly “see” localized deformation in the form of irreversible, and potentially fatal, localized slip. In this study, near-field and far-field HEDM are coupled with a new data reduction technique to track a signature of localized deformation in an Inconel-718 superalloy subjected to fully reversed cyclic loading. This signature, constructed from intragranular stress and orientation distributions, allows us to indirectly detect the presence of localized slip and focus our study on the most critical grain neighborhoods.