Advanced Characterization Techniques for Quantifying and Modeling Deformation: Phase Transformation Plasticity, Grain Boundaries, and Interfaces
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS Structural Materials Division, TMS: Shaping and Forming Committee, TMS: Materials Characterization Committee
Program Organizers: Rodney McCabe, Los Alamos National Laboratory; Thomas Bieler, Michigan State University; Marko Knezevic, University of New Hampshire; Irene Beyerlein, University of California, Santa Barbara; Wolfgang Pantleon, Technical University of Denmark; C. Tasan, Massachusetts Institute of Technology; Arul Kumar Mariyappan, Los Alamos National Laboratory
Monday 8:00 AM
February 24, 2020
Room: Theater A-2
Location: San Diego Convention Ctr
Session Chair: Eric Homer, Brigham Young University; Amy Clarke, Colorado School of Mines
8:00 AM Invited
TRIP/TWIP of Structural Metallic Alloys for Performance in Extreme Environments: Amy Clarke1; Benjamin Ellyson1; John Copley1; Francisco Coury2; Jonah Klemm-Toole1; Yaofeng Guo1; Jinling Gao3; Chandler Becker1; Brian Milligan1; Christopher Finfrock1; Chloe Johnson1; Kester Clarke1; Wayne Chen3; Niranjan Parab4; Tao Sun4; Kamel Fezzaa4; 1Colorado School of Mines; 2Universidade Federal de São Carlos; 3Purdue University; 4Advanced Photon Source, Argonne National Laboratory
TRansformation Induced Plasticity (TRIP) and TWinning Induced Plasticity (TWIP) are deformation mechanisms commonly employed in the design of Advanced High Strength Steel (AHSS) microstructures that exhibit desirable combinations of strength and ductility for crash management in automotive applications. Yet, these deformation mechanisms are underutilized and less understood in lightweight metallic alloys such as Ti, important for aerospace, defense, and biomedical applications. Here we use in-situ imaging and diffraction at the Advanced Photon Source at Argonne National Laboratory to study TRIP/TWIP behavior in metastable beta-Ti and multi-principal element alloys (MPEAs) during dynamic loading in tension and compression at strain rates up to approximately 103 s-1. Quasi-static and intermediate strain-rate testing and detailed microstructural characterization are also performed to support the development of experimentally-validated modeling. Fundamental understanding of TRIP/TWIP will enable novel alloying and processing strategies to create microstructures and properties by design for performance (e.g. blast resistance) in extreme environments.
8:30 AM
A Critical Assessment of the Dual-TRIP Effect: Beneficial or Not?: Shaolou Wei1; Jinwoo Kim1; Cemal Tasan1; 1Massachusetts Institute of Technology
Classical transformation-induced plasticity (TRIP) effect is considered as one of the most effective strain hardening mechanisms in metallic alloys. While appreciable effort has been accomplished to maximize the strain hardening contribution of this mechanically-induced transformation in Fe-based alloys, the resultant transformation product, ferrous martensite, possesses extensive defect density and limited strain hardenability, which inevitably leads to local embrittlement. In this presentation, we will demonstrate that the parent-FCC phase in an Fe-Mn-rich alloy can exhibit the strain-induced HCP-martensitic transformation, and the resulting HCP phase can further transform, activating a mechanically-induced FCC-HCP-FCC dual-TRIP effect. With the aid of in-situ synchrotron X-ray diffraction, integrated SEM/EBSD, and microstructural-based strain mapping techniques we reveal the corresponding deformation micro-mechanisms including transformation kinetics, kinematics, and global-local strain evolution. We will show that this sort of dual-TRIP mechanism exhibits a desirable potential to overcome the inherent property improvement limit of classical-TRIP effect.
8:50 AM
Investigating the Microstructure and Mechanical Behavior Relationship of Advanced Titanium Alloys Using High-energy Diffraction In-situ Tensile Testing: Priya Ravi1; Diwakar Naragani1; Jun-Sang Park2; Kartik Kapoor1; Ryan Noraas3; Vasisht Venkatesh3; Jonathan Almer2; Michael Sangid1; 1Purdue University; 2Argonne National Laboratory; 3Pratt & Whitney
In this study, the role of composition and microstructure on the mechanical behavior of three advanced titanium alloys – Ti-6Al-4V, Ti-6Al-2Sn-4Zr-2Mo, and Ti-6Al-2Sn-4Zr-6Mo is investigated using multiple characterization techniques. Their microstructures were characterized using backscattered electron (BSE) images and their deformation behaviors were explored using high-energy x-ray diffraction in situ uniaxial tension tests. The evolution and hardening responses of the lattice strains for the α and β phases are discussed. Stress-induced β→ α" phase transformation was also observed in Ti6246, which was captured during the in situ diffraction experiment. Results from this study provide insights into the relationship between microstructure, composition, and mechanical behavior.
9:10 AM Invited
Simulations of Grain Boundary-dislocation Interactions in FCC Nickel: Eric Homer1; David Page1; Devin Adams1; Ricky Wyman1; David Fullwood1; Robert Wagoner2; 1Brigham Young University; 2Ohio State University
Grain boundary-dislocation interactions play a crucial role in the deformation behavior of polycrystalline materials. While it is well known that grain boundaries can respond in a variety of ways to imposed deformation, the criteria for each response is not well known. We present work focused on determining the criteria for nucleation of dislocations from a grain boundary as well as efforts to determine the criteria for transmission of dislocations through a grain boundary. The nucleation simulations of a single grain boundary find unique criteria for every slip system, which include non-Schmid effects. The transmission simulations sample a larger population of grain boundaries and find more variation in the observed geometric criteria and resolved shear stresses. We also detail efforts to work beyond the limitations of our current approaches.
9:40 AM Break
10:00 AM Invited
Characterization of 3-D Slip Fields in Deforming Polycrystals: Darren Pagan1; Kelly Nygren1; Matthew Miller2; 1Cornell High Energy Synchrotron Source; 2Cornell University
The interactions of slip systems at grain boundaries have been posited to be a critical factor in the nucleation of damage, especially during the dwell fatigue process in titanium alloys. To test these hypotheses, 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 lattice orientation fields made using high-energy X-ray diffraction microscopy with crystal plasticity kinematics to reconstruct full 3-dimensional slip activity fields with micron-scale resolution. The utility of the method will be demonstrated through analysis of slip activity in Ti-7Al deformed in uniaxial tension with a focus on analyzing slip mismatch at grain boundaries.
10:30 AM
Slip and Hydrides in Zirconium: Siyang Wang1; Finn Giuliani1; Thomas Britton1; 1Imperial College London
Zirconium is used in nuclear fuel cladding materials in water reactors, where due to corrosion there can be hydrogen pick up. This can form hydrides which decorate the microstructure, and can impact the mechanical performance of zirconium alloys (Zircaloy-4) which affects the structural integrity of the cladding material. We have used micromechanical testing to explore the local interaction of <a> basal and <a> prism slip with hydride interfaces selected using EBSD of large grain ‘blocky alpha’ zircaloy-4, focussing on property extraction using micropillar compression and direct observation of slip-hydride interface mechanics. In this talk, we will explore how hydrides affect hardening and the slip transmission through interfaces thereby changing the local mechanical performance. The consequences of the interaction of slip and hydride for polycrystalline deformation will be explored using polycrystal tests with high resolution digital image correlation (HR-DIC).
10:50 AM
A Quantitative Study of Slip Band-Grain Boundary Interactions in Mg Alloys: Mohsen Taheri Andani1; Aaditya Lakshmanan1; Veera Sundararaghavan1; John Allison1; Amit Misra1; 1University of Michigan
Understanding dislocation interactions with grain boundaries (GBs) is key to assess the strengthening in metallic materials. Among studies to quantify such phenomena and their effects on the mechanical properties, the microscopic Hall-Petch relationship has been proposed which claims that the flow stress of a slip system is inversely proportional to the square root of the grain size. Despite some theoretical analysis dedicated to studying the role of GB parameters on the flow stress of a slip system, the experimental capability to measure the stress-field induced by dislocations blocked by a GB and its subsequent effect on the flow stress is still limited. The objective of this work is to utilize high-resolution electron backscatter diffraction technique combined with a dislocation pile-up model to estimate the microscopic Hall-Petch coefficients for different GB type. This research will provide new insights into the understanding of the GB effect in the plasticity of Mg alloys.
11:10 AM
Room Temperature Interface Sliding in TIMETAL-407: Zachary Kloenne1; Gopal Viswanathan1; Matt Thomas2; Michael Loretto3; Hamish Fraser1; 1Ohio State University; 2TIMET; 3University of Birmingham
Titanium alloys are excellent candidates for aerospace applications owing to their high strength to weight ratio. Alpha/beta titanium alloys are used in nearly all sections of the aircraft, including the fuselage, landing gear, and wing. Ti-0.85Al-3.9V-0.25Si-0.25Fe (Ti-407) is an excellent candidate for alloy applications requiring excellent machinability and increased energy absorption. Through a combination of electron backscattered diffraction (EBSD) and diffraction contrast imaging, it was determined that the alloy deforms significantly by <c+a> slip in both hard and soft grains. More surprisingly, Ti-407 has also been shown to deform by interface sliding during room temperature tensile tests. The nature of this sliding has been investigated using in-situ straining in a scanning electron microscope (SEM). The alpha/beta interface was explored using atom probe tomography (APT) and high resolution scanning transmission electron microscopy (HRSTEM) to provide insight on the cause of interface sliding.
11:40 AM Cancelled
Reversible Phase Transformations in a Metastable Beta Titanium Alloy Resolved with Quantitative Electron Microscopy: Kui Du1; Lu Qi1; Chunjin Chen1; Yulin Hao1; Rui Yang1; Hengqiang Ye1; 1Institute of Metal Research
Metastable beta-Ti alloys are a highly promising multifunctional material attributed to their unique properties combining high strength, low elastic modulus, super-elastic properties and excellent biocompatibility. Mechanical properties of these alloys are strongly influenced by the presence of various intermediate phases such as omega, alpha and alpha" phases. Since both high super-elasticity and good shape memory are utilized for the applications of beta-Ti alloys, the reversibility of these phase transformations becomes an important issue for developing the properties. Here, a reversible omega transformation has been directly observed in a metastable beta-Ti alloy during in situ tensile deformation with aberration corrected high-resolution transmission electron microscopy. The trigonal symmetry of the omega phase and the continuous transition interfacial structure between the product and parent phases ensure the occurrence of the reversible transformation. These in-depth understanding on the phase transformation mechanisms are of great significance to optimize mechanical and functional properties of Ti-alloys.