Mechanical Response of Materials Investigated through Novel In-situ Experiments and Modeling: Session VI
Sponsored by: TMS Structural Materials Division, TMS Functional Materials Division, TMS: Advanced Characterization, Testing, and Simulation Committee, TMS: Thin Films and Interfaces Committee
Program Organizers: Saurabh Puri, VulcanForms Inc; Amit Pandey, Lockheed Martin Space; Dhriti Bhattacharyya, Australian Nuclear Science and Technology Organization; Dongchan Jang, Korea Advanced Institute of Science and Technology; Shailendra Joshi, University of Houston; Minh-Son Pham, Imperial College London; Jagannathan Rajagopalan, Arizona State University; Robert Wheeler, Microtesting Solutions LLC; Josh Kacher, Georgia Institute of Technology
Thursday 2:00 PM
March 23, 2023
Room: Aqua 310B
Location: Hilton
Session Chair: Ryan Hurley, Johns Hopkins University; Alain Reiser, KTH Royal Institute of Technology
2:00 PM Invited
Advances in Micromechanics and Digital Twin Modeling of Concrete and Geologic Materials Aided by In-situ Tomography and 3D X-ray Diffraction: Ryan Hurley1; Mohmad Thakur1; Ghassan Shahin1; 1Johns Hopkins University
Concrete and rocks are characterized by significant structural heterogeneity. Under mechanical loading, this structural heterogeneity gives rise to stress heterogeneity and complex load sharing between phases. Complex micromechanics remains an area of active research. Digital twin modeling offers some promise for exploring this complexity using a digital testbed. Here, we describe two thrusts of our research related to stress heterogeneity and digital twin modeling. First, we describe the development and use of small-scale samples and testbeds for studying structure, grain-resolved stress tensors, and intra-grain stress fields in mechanically-compressed concrete and rocks using in-situ x-ray tomography, 3D x-ray diffraction (far-field high energy diffraction microscopy), and scanning 3D x-ray diffraction. We discuss the insight these measurements provide regarding stress heterogeneity and load sharing between phases. Next, we discuss the construction and use of digital twin models for concrete that are validated with the multi-modal x-ray measurements.
2:30 PM
Advanced Impactors for Laser-induced Particle Impact Testing: Alain Reiser1; Christopher Schuh1; 1Massachusetts Institute of Technology
Laser-induced particle impact testing (LIPIT) is a tabletop, high-throughput technique for the study of materials’ behavior upon deformation at highest strain rates. The first decade of high-velocity microparticle impact research was characterized by the use of spherical impactors. However, future avenues for the field are certainly to be found with alternative impactor shapes that can unlock alternative loading states. As a step towards high-fidelity control of impactor shapes, this talk will introduce the use of microfabricated projectiles for LIPIT. We will review experimental challenges in both fabrication and use of microscale metal disks for LIPIT and outline future opportunities in projectile engineering.
2:50 PM
Atomistic Perspective of Grain Boundary Plasticity in Metals: Qi Zhu1; Haofei Zhou2; Huajian Gao1; Jiangwei Wang2; 1Nanyang Technological University; 2Zhejiang University
Grain boundary (GB) as an indispensable defect sustaining the structural integrity and mass transport of materials can significantly contribute to the plastic deformation, and the theory of GB plasticity keeps advancing. Combining state-of-the-art in situ transmission electron microscopy nanomechanical testing and multi-scale simulations, the atomistic evolutions of GBs in metals under external loading can be unambiguously revealed. In essence, the nucleation, propagation and interactions of inherent disconnections leads to shear-coupled GB migration, which applies to the plasticity of GB networks. Besides, the structural evolution of GBs can coordinate with intragranular plasticity such as deformation twinning, thereby dynamically adjusting the mobility of GBs and tuning the mechanical responses of metallic materials. These findings consolidate a series of missing puzzles for developing the full map of GB-mediated deformation, furnishing our understanding of GB plasticity. This talk is based on our recent papers on Nature Communications (2021) and Science Advances (2022).
3:10 PM
Compressive Behavior of Pure Polycrystalline Cobalt and Other HCP Metals Investigated Using Acoustic Emission: Adam Gres1; Michal Knapek1; Patrik Dobroň1; Peter Minárik1; František Chmelík1; 1Charles University
To assess the dependency of the compressive behavior of pure polycrystalline cobalt on the residual fcc phase content, samples are prepared first undergoing isothermal annealing at different temperatures. This leads to recrystallization and grain growth, allowing for targeted modification of the microstructure. Annealing at such temperatures leaves residual high temperature fcc phase in the material. Additional thermal cycling around the phase transition temperature was applied. This leads to grain growth and a significant drop of the fcc phase content. Dependence of the compressive behavior on the microstructure is subsequently examined using deformation testing with constant speed of deformation combined with acoustic emission (AE). Additional testing was performed with Mg and Ti samples. Further analysis of acquired AE data provides an in-depth look at the deformation mechanisms that take place in the observed materials. Observed power law distribution of the AE event parameters confirms the collective nature of the dislocation motion.
3:30 PM Break
3:50 PM
In situ Extreme Micromechanics – Recent Innovations and Prospects: Remo Widmer1; Nicholas Randall1; Renato Pero1; Jean-Marc Breguet1; 1Alemnis AG
Micromechanical experiments are moving beyond basic hardness and elastic modulus measurements at ambient conditions. We present how novel instrumentation enables small-scale compression, tension, shear, splitting, push-out, fatigue, creep, and other techniques, at extreme conditions such as cryogenic to high temperatures, ultra-high strain rates, and high humidity levels. Moreover, we demonstrate the combination of multiple extreme conditions. For instance, high strain rate experiments up to 104 s-1 can be performed at temperatures ranging from -150 °C up to 1000 °C. Exploring the mechanical behaviour of materials as a function of multiple extreme variables paves the way to understand and predict the performance of components in extreme real-world applications such as aerospace, fuel cells, and nuclear reactors, amongst others. Finally, future research directions in the field of in situ extreme micromechanics will be discussed, including the prospect of ultra-low temperatures, hydrogen environments, and extreme radiation fluxes.
4:10 PM
Optically Pumped Magnetometer Measuring Fatigue-induced Damage in Steel: Thomas Straub1; Ali Riza Durmaz1; Simon Philipp1; Andreas Blug2; Alexander Bertz2; 1Fraunhofer Institute for Mechanics of Materials (IWM); 2Fraunhofer Institute for Physical Measurement Techniques (IPM)
Uniaxial fatigue testing of micro-mechanical metallic specimens can provide valuable insight into damage formation. Magnetic testing are used for qualitative characterization of damage in ferromagnetic specimens. Sensitive and accurate measurements with magnetic sensors are a key part of such a characterization. This work presents an experimental setup to induce structural defects in a micro-mechanical fatigue test. The resulting magnetic signals are measured during the complete lifetime of the tested specimen. The key component is a highly sensitive optically pumped magnetometer (OPM) used to measure the magnetic hysteresis of a small specimen whose structural defects can be analyzed on a small scale by other metallographic characterization methods as well. This setup aims to quantify the magnetic signatures of damage during the fatigue process, which could enable non-destructive mechanical testing. The initial results obtained from this novel micro-magneto-mechanical test setup for a ferritic steel specimen will be reported in this talk.
4:30 PM
Stress-strain Responses from Spherical Nanoindentation and Micro-pillar Compression Experiments in Fe-3% Si: A Comparative Study: Soumya Varma1; Sid Pathak1; Jordan Weaver2; Surya Kalidindi3; Johann Michler4; 1Iowa State University; 2NIST; 3Georgia Institute of Technology; 4EMPA
Spherical nanoindentation and micro-pillar compression experiments were conducted on large (millimeter sized) individual grains of different orientations in two sets of Fe-3%Si (BCC) polycrystalline samples (as-cast, 30% deformed). The indentation loading moduli, yield strength, and post-yield strain hardening behavior were obtained by transforming raw indentation load-displacement data into stress-strain curves. Micro-pillars of varying diameters were FIB machined on the same grains, then in-situ SEM compression tested to identify yield strength and strain hardening behavior. Local crystal lattice orientations were measured by electron backscatter diffraction. Slip resistances calculated from indentation (155.4 ± 3.5 MPa) and pillars (201 ± 28 MPa) are in good agreement. From these results, we estimate the percentage increase (16%change in during indentation) in slip resistance of the deformed polycrystalline cubic metals from their fully annealed condition. Advantages and limitations of each technique to capture plastic anisotropy and changes in slip resistance are discussed.