Advanced Characterization Techniques for Quantifying and Modeling Deformation: Session VIII
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
Thursday 2:00 PM
March 23, 2023
Room: Aqua 311A
Location: Hilton
Session Chair: Mohamed Hamza, Arizona State University; Daryl Chrzan, University of California
2:00 PM Invited
The Relationship between Dislocation Core Structures and Oxygen Sensitivity in α-Ti: Daryl Chrzan1; Eric Rothchild1; Max Poschmann1; Siying Li1; Ian Winter1; Yan Chong1; Ruopeng Zhang1; Shiteng Zhao1; Mohammad Hooshmand1; David Olmsted1; John W. Morris1; Mark Asta1; Andrew Minor1; 1University of California, Berkeley
Interstitial oxygen is a potent strengthening and embrittling agent within pure Ti. Substitutional Al is also known to decrease Ti’s ductility at low O concentrations. However, when deformed at cryogenic temperatures, introduction of both impurities at relatively high concentrations increases the strength and the ductility of the alloy. Interestingly, many of these observations can be related to the ease with which dislocations will cross-slip onto alternate glide planes. Dislocation cross slip, in turn, is influenced strongly by structure of the dislocation cores. For Ti, the relevant dislocations are a-type screws, which have a tendency to spread on a number of competing slip planes. We argue that both temperature and solute interaction induced fluctuations in this spreading can account for the experimental observations, and that this understanding is key to engineering improved Ti alloys.This work is supported by the Office of Naval Research.
2:30 PM
The Characteristics of Strain Burst Acoustic Emissions during In Situ Microcompression Experiments: Mostafa Omar1; Jaafar El-Awady1; 1Johns Hopkins University
Plasticity at the microscale is manifested in an intermittent fashion compared to the smooth bulk behavior. Studying the deformation mechanisms using in-situ micromechanical testing solely is limited to capturing the extrinsic collective behavior of the deformation activities. Acoustic emission (AE) technique is capable of deconvoluting the spatiotemporal overlap as well as capturing the inherent behavior of the active mechanisms. In this work, we report the successful employment of AE technique coupled with in-situ testing in studying the behavior of the strain bursts in Ni single crystals. Bursts were classified into fast and slow. Fast burst occurred at the early deformation stages and possessed large burst sizes. Early fast bursts were found to generate the loudest waves (highest energies and amplitudes). Released AE energies decayed as deformation progressed, nearly saturating at < 10% strain. Measured AE energies were proportional to the dissipated energies calculated from the stress-strain data.
2:50 PM
Characterizing Structure and Deformation in Molecular Dynamics Simulations of Shock Compressed Silicon and Diamond Carbon: Alex Li1; Rob Rudd2; Boya Li1; Marc Meyers1; 1University of California San Diego; 2Lawrence Livermore National Labs
Silicon and Diamond are covalently bonded materials that share an ambient crystalline diamond cubic structure. The shock structure of silicon is investigated through classical molecular dynamics simulations in the range of 10-20 GPa using the modified Tersoff interatomic potential. Simulations in the literature have shown presence of amorphous regions at the areas with high dislocation density; however, the disordered structure outside of those amorphous regions was not fully identified. The structure is characterized here using radial distribution and angular distribution functions comparing pristine silicon structures with those within the shocked silicon bulk. Additionally, measurements are made of the flow stress and energy stored by the phase change within the shocked regions. These simulations are extended to modeling shock compression of diamond carbon, including the addition of voids and polycrystalline grain boundaries, and observing the deformations and structural changes that occur.
3:10 PM
Effect of Self-Annealing Phenomena on the Microstructural and Texture Evolution in Cryogenically Rolled Cu-Fe-P alloy: Aman Gupta1; Lalit Kaushik1; Tae-Hyeon Yoo1; Shi-Hoon Choi1; 1Sunchon National University
In the present study, Cu-Fe-P specimens were subjected to the 20%, 40%, 60%, and 80% reduction ratio (RR) through cryogenic rolling (CR). High-resolution EBSD was used to characterize the microstructural evolution in CR specimens. Severely deformed CR specimens showed the formation of strain localizations (SLs), which were predominantly formed in the Copper-type grains. Self-annealing phenomena was observed in the severely deformed CR specimens which causes the grain nucleation at the deformed GBs and at the SLs. Nucleation of new grains confirms the activation of discontinuous SRX (DSRX) and continuous SRX (CSRX) in CR Cu-Fe-P alloy specimens. Initial Cu-Fe-P specimen showed weak plane strain texture whose intensity goes on increase with the increase in RR. SRX at SLs shows the preferential formation of Copper, Brass, and S nucleated grains in the CR-80 specimen. Time-dependent decay in the hardness values for the CR specimens, attributing to the SRV and SRX.
3:30 PM Break
3:50 PM
Numerical Investigation of the Strain Development at the Substrate / Laser Metal Deposition - Powder Refurbishment Interface: Romain Bordas1; Mathieu Calvat1; Jonathan Cormier1; Azdine Nait-Ali1; Patrick Villechaise1; Roland Fortunier2; 1Ensma - Institut Pprime - Upr Cnrs 3346; 2LTDS, école centrale Lyon / ENISE, on secondment to ENSMA
Numerous studies reported the mechanical properties of additive manufactured superalloys, but only a few focused on the mechanical response of the interface between the deposited material and the substrate. In this study, EBSD characterizations have been performed at the interface between a cast and wrought Waspaloy and a Laser Metal Deposition – Powder Waspaloy deposit to generate a representative synthetic 3D aggregate. This process locally impacted the microstructure which led to a 350-µm-thick Heat Affected Zone with a degraded γ' precipitation and an increased grain size. Then, full-field macro-homogeneous and crystal plasticity FE have been carried out on 2D-extruded from experimental EBSD data and synthetic 3D aggregate. For each microstructure, substrate or deposit have been treated independently and together. Strain and stress fields have enabled to highlight the influence of the refurbishment as well as microstructural characteristics gradient on the development of "hot spots" in terms of strain localizations.
4:10 PM Cancelled
Characterization and Mechanical Testing of Ordinary Chondrites: Mohamed Hamza1; Charles Galluscio2; M.F. Rabbi1; Laurence Garvie1; Desireé Cotto-Figueroa3; Erik Asphaug4; Aditi Chattopadhyay1; 1Arizona State University; 2University of Florida; 3University of Puerto Rico at Humacao; 4University of Arizona
Understanding the deformation mechanisms and mechanical properties of asteroids that are Near-Earth Objects is crucial in developing hazard mitigation strategies, as well as unraveling its potential engineering applications. A comprehensive study of the microstructure and mechanical behavior of Viñales (L6) ordinary chondrite is conducted. First, optical microscopy and micro-CT are applied for microstructure characterization. Next, the mineral composition and textures are determined using a scanning electron microscope equipped with wavelength-dispersive spectrometers. The Brunauer-Emmett-Teller (BET) method is used to measure the surface area and determine the pore-size distribution. Quasi-static compression tests, accompanied with in-situ digital-image correlation are utilized to determine the global strength of the material as well as localizing the regions of excessive deformation and failure. Finally, a fracture mechanics-based model is developed and applied to a representative volume element to understand the effect of different material flaws and phases on the wing micro-crack propagation and subsequent brittle failure.