Advanced Characterization Techniques for Quantifying and Modeling Deformation: Session VI
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
Wednesday 2:00 PM
March 22, 2023
Room: Aqua 311A
Location: Hilton
Session Chair: Mohsen Taheri Andani, Texas A&M University; Laurent Capolungo, Los Alamos National Laboratory
2:00 PM Invited
Twin Network Formation and Morphology in Metals with Hexagonal Close Packed Crystal Structure: Laurent Capolungo1; Dang Khanh1; Arul Kumar1; Darshan Bamney1; Hi Vo1; Rodney McCabe1; Carlos Tome1; 1Los Alamos National Laboratory
Plasticity in metals with the hexagonal close packed crystal (hcp) structure can be simultaneously mediated by the activation of slip and twinning. The role of twinning on the plastic response of hcp metals likely correlates with the kinetics and mechanisms of formation of twin networks. Using atomistic simulations, phase field modeling, and a novel tool, METIS-3D - allowing for the reconstruction of three-dimensional (3D) twinned volumes from the use of serial 3D ESBD, we studied the unit processes (i.e., twin transmission across grain boundaries) leading to the formation of complex twin networks. The study demonstrates that inter and intra-granular stresses determine the outcome of twin/grain boundary interactions. In contrast, geometrical requirements (i.e., alignment between incoming and outgoing twins) do not significantly constrain the transmission process. Altogether, these mechanisms translate into complex and tortuous twin networks that as revealed and analyzed in 3D for the first time in Ti.
2:30 PM
High Orientation Precision 3D-EBSD with Multi-Modal Data Registration: Gregory Sparks1; Paul Shade2; Michael Uchic2; Stephen Niezgoda1; Simon Mason1; Michael Mills1; Mark Obstalecki2; 1Ohio State University; 2Air Force Research Laboratory
In this talk, we discuss the results of high orientation precision 3D-EBSD from serial sectioning with spherical harmonic indexing. We highlight various difficulties that arose from the increased orientation precision, such as an increased sensitivity to surface preparation quality or minor sample alignment issues, along with the solutions we implemented to resolve these issues. We also demonstrate registration of the 3D-EBSD data with multiple other data modalities, including zero-tilt optical and backscattered electron imaging, as well as near-field and far-field high-energy diffraction microscopy. We also demonstrate analysis of fine microstructural details in specific grains using electron channeling contrast imaging, further extending the level of detail that can be obtained in three-dimensional microstructural analysis.
2:50 PM
Evolution of Stresses during Twinning and Detwinning in Magnesium: Karim Louca1; Jonathan Wright2; Marta Majkut2; Hamidreza Abdolvand1; 1University of Western Ontario; 2European Synchrotron Radiation Facility (ESRF)
Understanding deformation mechanisms of hexagonal close packed (HCP) metals at multiple length scales is essential for developing predictive materials models. Due to its high strength to weight ratio and its importance in several industrial sectors including the transportation industry, magnesium is used in this study. Three-dimensional synchrotron X-ray diffraction (3D-XRD) experiment is performed on magnesium specimens to investigate the development of grain resolved tensorial stresses during twinning and detwinning. More than 13,000 grains and 1,300 twin-parent pairs were captured during in-situ compression-tension tests. Here we show that at the early stages of plasticity, the axial stresses in the twins are higher than the parent grains but relax with further loading. During detwinning, a sign reversal is observed for the resolved shear stress (RSS) acting on the twin habit plane in the parent grain, while the sign of RSS in twins remains the same until total twin annihilation.
3:10 PM
Micro Hall-Petch Slope in Mg Alloys: The Influence of Grain Boundary Parameters: Mohsen Taheri Andani1; Aaditya Lakshmanan1; Jeremy Yoo1; Veera Sundararaghavan1; John Allison1; Amit Misra1; 1University of Michigan
The Hall-Petch effect, also known as grain size strengthening, is a common method for increasing the strength of magnesium (Mg) alloys. According to several studies, the geometry and structure of grain boundaries (GBs) in polycrystalline materials substantially affect the Hall-Petch slope. Nevertheless, experimental results are constrained by the techniques' ability to measure the GB barrier strength to dislocation glide and validate these theories. In this study, a high-resolution electron backscatter diffraction technique is applied in conjunction with a dislocation pile-up model to measure the barrier strength of various GBs to different slip systems, known as the micro Hall-Petch slope in Mg-4Al. The method for including the micro Hall-Petch equation in crystal plasticity constitutive models that take into account the microstructural is provided. This study will shed light on the role of texture, grain size, and loading direction on the plasticity of Mg alloys.
3:30 PM Break
3:50 PM
An In-Situ Study of Mechanical Twinning Effects on Strain Localization and Damage in an (α+β) Titanium Alloy: Jiyun Kang1; C. Cem Tasan1; 1Massachusetts Institute of Technology
Clarifying micro-mechanisms that cause strain heterogeneity in multi-phase titanium (Ti) alloys is of fundamental importance for more damage-resistant microstructure design. The occurrence of mechanical twinning increases the difficulties in characterization due to its spatial and time dependence. In this study, we combine the insights provided by in-situ microstructure-based digital image correlation (μ-DIC) and in-situ synchrotron X-ray diffraction (SXRD) to shed more light on the effects of mechanical twinning on strain localization and damage evolution in an (α+β) alloy. Strain localization mechanisms in the alloy are investigated in a timely and spatially resolved manner. The potential use of mechanical twinning to delocalize plastic strain will also be discussed.
4:10 PM
Capturing the 3D Evolution of Twin Networks in Titanium as a Function of Applied Strain: Hi Vo1; Rodney McCabe1; Patrick Pinney1; Matthew Schneider1; M. Arul Kumar1; Carlos Tome1; Laurent Capolungo1; 1Los Alamos National Laboratory
Deformation twinning has been extensively studied as it plays a dominant role in the plastic deformation and strengthening in hexagonal closed packed (HCP) metals. Twin-twin interactions, twin-boundary interactions, and other characteristic features of twin networks have been studied extensively via electron backscatter diffraction (EBSD) in two dimensions (2D). However, the 2D characterization techniques fail to capture some of the important aspects of how three-dimensional neighborhoods influence twin network evolution. In this study, we utilized plasma-FIB (PFIB) based 3D-EBSD to capture the 3D evolution of twin networks in high-purity titanium compressed to several strain levels. Statistical analysis is performed to identify the characteristic features (e.g. twin chains, twin junctions) that govern the evolution of the 3D microstructure as a function of applied strain. One of the findings suggests that twin chain in 3D is much longer than we previously thought.
4:30 PM
Slip Transfer at Grain Boundaries and Intergranular Fracture in Ti: Eugenia Nieto1; Eshan Ganju2; Nik Chawla2; Javier Llorca1; 1IMDEA Materials Institute & Technical University of Madrid; 2Purdue University
A strategy based on experiments and simulations is presented to ascertain the influence of 3D grain boundary orientation on the deformation mechanisms of pure Ti. Thin foils of commercially pure Ti were subjected to uniaxial tensile loading. The microstructure was characterized by means of laboratory x-ray diffraction contrast tomography (LabDCT) to obtain information about the crystallographic orientation of the grains as well as about the grain boundary geometry on the specimen surface and through the thickness. The occurrence (or not) of slip transfer across the grain boundaries as well as intergranular cracking was ascertained in more than 300 grain boundaries from slip trace analysis coupled with high-resolution digital image correlation on the surface of deformed specimens. In parallel, the mechanical behaviour of the polycrystals was simulated with a dislocation-based crystal plasticity model where fracture was included by means of cohesive surfaces at the grain boundaries.
4:50 PM
Dislocation Pile-ups and Grain Boundary Interactions Studied Using In Situ Cross-Correlation EBSD in High Purity Nickel: Yang Su1; Thanh Phan2; Liming Xiong2; Josh Kacher1; 1Georgia Institute of Technology; 2Iowa State University
To study how grain boundary character affects grain boundary strength, high-resolution electron backscatter diffraction (HR-EBSD) analysis was conducted at ~50 grain boundaries in high purity nickel during in situ tensile deformation. Elastic strain gradients associated with the pileups were investigated, which were then used to calculate the stress buildup at the boundary. By comparing the stress along a slip band at different strain levels, it was found that the evolution of the stress tensor is related to the grain boundary character and the geometrical relationships of the slip bands across the boundary, with both stress increases and load drops after critical stress levels observed. Atomistic-to-microscale simulations were used to investigate the details of the interactions. This evolution in local stress as a function of applied strain will be discussed in terms of grain boundary and geometrical metrics, including m’, residual Burgers vector, strain energy density, and grain boundary coherency.
5:10 PM
Deformation Behavior of Chondrite Meteorite Using In Situ Correlative Microscopy: Tai-Jan Huang1; Eshan Ganju1; Hamid Torbatisarraf1; Sridhar Niverty1; Nikhilesh Chawla1; 1Purdue University
Meteorites possess complex microstructures due to formation and structure evolution events spanning through astronomically long periods, along with extreme conditions in which they were formed. The resulting anisotropic structure makes precise structure-property studies challenging. Hence, a comprehensive understanding of how microstructural phase distribution and their respective mechanical properties connect to macro deformation behavior is crucial. In this study, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) was utilized to characterize meteorite Aba Panu (L3). In situ compression experiments were performed on machined cylindrical samples of meteorite. The crack development was studied via x-ray microtomography (XRT). Direct 3D correlation of in situ images of crack growth were used to form a comprehensive mechanistic understanding of crack development and deformation. Nanoindentation was used to complement the imaging study to obtain mechanical properties of individual constituent phases to round out this comprehensive multi-scale study.