Integration between Modeling and Experiments for Crystalline Metals: From Atomistic to Macroscopic Scales II: Session IV
Program Organizers: Arul Kumar Mariyappan, Los Alamos National Laboratory; Irene Beyerlein, University of California, Santa Barbara; Levente Balogh, Queen's University; Josh Kacher, Georgia Institute of Technology; Caizhi Zhou, University of South Carolina; Lei Cao, University of Nevada
Thursday 8:00 AM
November 5, 2020
Room: Virtual Meeting Room 35
Location: MS&T Virtual
Session Chair: Yu Wang, Michigan Technological University; Robert Suter, Carnegie Mellon University
8:00 AM Invited
Synchrotron X-ray Tools for Multiscale Studies of Microstructure Evolution: Matthew Wilkin1; Yueheng Zhang1; Yufeng Shen1; He Liu1; Anthony Rollett1; Robert Suter1; 1Carnegie Mellon University
High energy x-ray diffraction microscopy (HEDM) makes possible the in-situ observation of internal microstructure evolution at micron to millimeter length scales. Maps of crystal unit cell orientations and grain averaged strain tensors characterize cubic millimeter volumes of polycrystalline samples. Responses to thermal and mechanical loadings have been tracked. However, observed responses show emergent behaviors caused by unseen nanoscale defect motions. Development of predictive models requires experimental observations of the connections between these regimes. Defect motions have been observed in individual nanoscale particles using X-ray Bragg coherent diffractive imaging (BCDI) which is sensitive to atomic displacements on Angstrom length scales. With collaborators at Argonne and Los Alamos National Laboratories, we are working to combine BCDI with HEDM and scanning Laue diffraction methods in order to connect these measurements and length scales. An overview of progress will be given. Our work is supported by DOE/BES grant DESC0019096.
8:30 AM Invited
Experimental Capabilities at High Pressure Collaborative Access Team (HPCAT) for In-situ and In-operando Characterization of Pressure/Stress Induced Microstructural Changes in Materials: Dmitry Popov1; Nenad Velisavljevic2; 1HPCAT, X-ray Science Division, Argonne National Laboratory; 2Physics Division-Physical & Life Sciences Directorate, Lawrence Livermore National Laboratory
High Pressure Collaborative Access Team located at Sector 16 of Advanced Photon Source is an experimental facility for comprehensive characterization of materials behavior under extreme pressure-temperature conditions by multiple techniques based on synchrotron X-ray radiation. Overview of tools for pressure-temperature generation and to characterize microstructural changes during deformation, phase transitions and other pressure/stress induced processes will be presented, along with some recent case studies. The presentation will be focused on Laue diffraction technique recently developed at HPCAT for real time in-situ microstructural studies under high pressure or uni-axial deformation. Due to fast data collection Laue diffraction is a powerful tool for real time microstructural studies providing multiple orders of magnitude better time resolution, comparing to the most widely implemented monochromatic beam diffraction technique.
9:00 AM
Characterization of 3-D Slip Fields in Deforming Polycrystals: Darren Pagan1; Kelly Nygren2; Matthew Miller3; 1Pennsylvania State University; 2Cornell High Energy Synchrotron Source; 3Cornell University
The interconnecting interactions of crystallographic slip systems across ensembles of grains have been posited to be a critical factor in stress localization and subsequent nucleation of damage, especially during the dwell fatigue process in titanium alloys. To test these hypotheses, quantitative methods are needed to characterize slip activity in-situ in the bulk of deforming polycrystals. Here we present a new methodology that combines measurements of grain average stresses and spatially-resolved lattice orientation fields gathered using high-energy X-ray diffraction microscopy (HEDM) with crystal plasticity kinematics to reconstruct full 3-D slip activity fields at micron-scale resolutions. The utility of the method will be demonstrated through analysis of slip activity in Ti-7Al deformed under uniaxial tension with a focus on networks of slip developing through the deformed polycrystal.
9:20 AM
Diffraction Elastic Constants from Electron Backscatter Diffraction Data and Finite Element Models: Adam Creuziger1; Thomas Gnaupel-Herold1; Alex Bien1; Stephen Langer1; Andrew Reid1; 1National Institute of Standards and Technology
Diffraction elastic constants are used to convert lattice strain measurements to macroscopic stress values. In this work, we present a new method for calculating diffraction elastic constants and apply this method to the example of biaxially strained ferritic BCC (body centered cubic) steel. We incorporate EBSD (electron backscatter diffraction) data measured from biaxially strained samples into a finite element model (OOF2) and elastically strain the model to measure the diffraction elastic constants. In addition to providing values for the diffraction elastic constants, the EBSD based finite element model provides insight into the source of the experimentally observed non-linear behavior in the (211) reflection in BCC steels. The non-linear behavior is largely due to two clusters of grain orientations with different stiffness along the normal direction of the sheet.
9:40 AM Invited
Combining Multi-scale Modeling and Three-Dimensional Diffraction to Investigate Chemical and Displacement Ordering in Metallic Alloys: Yu Wang1; Yongmei Jin1; Yang Ren2; Xiaoxu Guo1; Liwei Geng1; 1Michigan Technological University; 2Argonne National Laboratory
A multi-scale material modeling is developed by integrating Density Functional Theory computation, microelasticity, and Monte Carlo simulation. Treating the total energy of an alloy as a sum of the energies of short-range chemical bonding and long-range elastic interaction, the model is applied to simulate disorder-order transitions of chemical and displacement natures and investigate long-range and short-range ordering phenomena. Computational diffraction of Bragg reflection and diffuse scattering are subsequently performed and compared with complementary experiments of three-dimensional high-energy synchrotron X-ray single-crystal diffraction, which are carried out to measure the fundamental and superlattice Bragg reflection peaks and diffuse scattering intensity distributions. As examples, the combined computational and experimental approach is applied to study atomic ordering in Fe-Ga alloys and displacement ordering in Ni-Mn-Ga alloys.
10:10 AM
Investigating the Microstructural Origins of Hydrogen Effects on Deformation and Fracture: Coleman Alleman1; Christopher San Marchi1; Brian Kagay1; 1Sandia National Laboratories
The mechanisms of hydrogen-assisted fracture in austenitic stainless steels are only superficially described in the literature. Here, we attempt to produce causal and quantitative evidence of hydrogen-affected deformation and fracture. We analyze oligocrystalline microstructures consisting of small numbers of large grains. This allows us to isolate deformation mechanisms in physical samples and to create computationally equivalent microstructures to simulate the experimentally-observed responses.This talk focuses on the development and application of a framework to simulate stress-strain responses of oligocrystal microstructures. This framework consists of a tool to assign a best-fit crystal orientation on a regular 2D grid, an application to simulate grain growth in a 3D volume with boundary conditions imposed by a 2D domain, and a crystal plasticity model capable of simulating the mechanical response of 3D microstructures. Preliminary simulations have been performed to study the interplay of morphology and hydrogen effects in the mechanical response of oligocrystals.