Integration between Modeling and Experiments for Crystalline Metals: From Atomistic to Macroscopic Scales II: Session III
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
Wednesday 8:00 AM
November 4, 2020
Room: Virtual Meeting Room 35
Location: MS&T Virtual
Session Chair: Yunzhi Wang, Ohio State University; David Field, Washington State University
8:00 AM
Electron Backscatter Diffraction Pattern Simulation for Interaction Volume Containing Lattice Defects: Chaoyi Zhu1; Marc De Graef1; 1Carnegie Mellon University
Despite the existence of numerous experimental studies on lattice defects with EBSD, there exists a lack of systematic understanding of the effects of defects on diffraction patterns. Early studies have shown that backscattered electrons are randomly generated inside the interaction volume, as prescribed by the Rutherford differential scattering cross-section. To accurately account for the effect of spatial distribution and density of defects on the diffraction pattern, interaction volume effect and depth-dependent local distortion of the crystal must be simultaneously considered. In this study, the integration of the approximate model for deformation inclusion in a master pattern with the depth-specific dynamical master pattern simulation allows us to produce a single weighted diffraction pattern summing up all the deformed depth master patterns contained within an interaction volume. Using this new method of pattern simulation, we have examined two cases: 1) a single edge dislocation; 2) a low angle grain boundary.
8:20 AM
Strong strain hardening in ultrafast melt-quenched
nanocrystalline Cu: the role of fivefold twins: Amir Hassan Zahiri1; Pranay Chakraborty1; Yan Wang1; Lei Cao1; 1Universitiy Of Nevada Reno
Low ductility due to the absence of strain hardening effect inthe nanocrystalline and nanotwinned metals is one of the recent challenges. In this work, we studied melt-quenched nanocrystalline Cu under compression, which contains high-density of fivefold twins (ffts), twin boundaries, and stacking faults and we observed sustained strain hardening effect. The molecular dynamics simulations show that the observed strain hardening is due to the contribution of numerous dislocation reactions, constant nucleation, dislocations impedance, and restricted twin boundary migration in fft networks. We find that dislocations can nucleate and impede by the ffts and migration of the fft boundary is restricted by its own core. Moreover, due to the gliding of two different Shockley partial dislocations in the opposite directions fft boundary migrates by two atomic planes directly. Finally, dislocation transmission observed among the fft boundaries. This work presents the advantage of ffts over nanotwins to overcome the strength-ductility trade-off.
8:40 AM Invited
Regulating Elastic and Plastic Deformations by Microstructure Design and Coupling between Deformation and Phase Transformation - An Integrated Modeling and Experimental Study: Qianglong Liang1; Yufeng Zheng2; Yipeng Gao3; Tianlong Zhang4; Dong Wang4; Michael Mills1; Hamish Fraser1; Yunzhi Wang1; 1Ohio State University; 2University of Nevada Reno; 3INL; 4Xi'an Jiao Tong University
In crystalline solids, shear deformations such as dislocation glide, mechanical twinning, and martensitic transformations share key common features such as autocatalysis by long-range elastic interactions and strain avalanche. In order to achieve the desired stress-strain behaviors for a given application, microstructures need to be tailored judiciously to have precisely controlled strain release during both elastic and plastic deformations. In this presentation, using a combination of theoretical modeling, computer simulation, and experimental characterization, we demonstrate how to utilize intrinsic and dynamic coupling between deformation and structural phase transformation to achieve unprecedented stress-strain behaviors in both structural and functional materials. This work is supported by DOE/BES program and NSF/DMREF program.
9:10 AM
Novel Remapping Method for HR-EBSD Based on Computer Vision Algorithm: Chaoyi Zhu1; Kevin Kaufmann2; Kenneth Vecchio2; 1Carnegie Mellon University; 2University of California, San Diego
In this study, the possibility of utilizing a computer vision algorithm, i.e., demons registration, to accurately remap electron backscatter diffraction patterns for high-resolution electron backscatter diffraction (HR-EBSD) applications is presented. First, the angular resolution of demons registration is demonstrated to be lower than the conventional cross-correlation based method, particularly at misorientation angles > 9˚. Second, demons registration is implemented as a first-pass remapping, followed by a second pass cross-correlation method, which results in angular resolution of ~0.5×10-4 rad, a phantom stress value of ~35 MPa and phantom strain of ~2×10-4, on dynamically simulated patterns, without the need of implementing robust fitting or iterative remapping. Lastly, the new remapping method is applied to a large experimental dataset collected from an as-built additively-manufactured Inconel 625 cube, which shows significant residual stresses built-up near the large columnar grain region and regularly arranged GND structures.
9:30 AM
Applications of Computational Polarized Light Microscopy for Large Area Orientation
Determination of alpha-Titanium: Ke-Wei Jin1; Marc De Graef1; 1Carnegie Mellon University
The texture of alpha-titanium, which has an HCP crystal structure, can greatly impact its mechanical properties. Additionally, alpha-titanium also exhibits anisotropic optical properties. When illuminated using polarized light, the HCP grains oriented in different directions reflect light as a function of the grain orientation. Using this behavior, the c-axis orientations of the grains can be determined. Compared to other techniques such as EBSD, computational polarized light microscopy (CPLM) is low cost and has the ability to accommodate large samples. We will present the use of CPLM in conjunction with a physics-based forward model (FM). Polarization aberration and methods for accounting for aberration will be discussed. Finally, we will present the use of CPLM to image large surface areas and perform texture analysis for large areas.
9:50 AM
Design of an Austenitic Steel Weldment System Using ICME: Daniel Bechetti1; Paul Lambert1; Jacob Steiner1; Matthew Sinfield1; Charles Fisher1; 1NSWC Carderock Division
Integrated Computational Materials Engineering (ICME) principles and methods have enabled accelerated development and transition of new materials in many industries. In order to establish and evaluate an ICME framework relevant to the design of naval materials, engineers at Naval Surface Warfare Center, Carderock Division and Naval Research Laboratory are engaged in a program to concurrently develop a base material and welding filler metal system using computational, statistical, and experimental methods. This presentation reports work to date on ICME investigations of heat affected zone (HAZ) and fusion zone (FZ) process-structure-property relationships in a novel austenitic steel alloy system. Topics covered will include modeling of HAZ and FZ microstructure evolution under the influence of multiple welding thermal cycles and optimization of filler metal composition for weldability and mechanical behavior using thermodynamic simulation, finite element analysis (FEA), and design of experiments (DOE) methods.