Bulletin of the American Physical Society
22nd Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 67, Number 8
Monday–Friday, July 11–15, 2022; Anaheim, California
Session M05: Defects and MicrostructureFocus Recordings Available
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Chair: Jon Eggert, Lawrence Livermore Natl Lab Room: Anaheim Marriott Platinum 3 |
Tuesday, July 12, 2022 4:00PM - 4:30PM |
M05.00001: Material property modification via ion implantation and its effects on strength and compressibility Invited Speaker: Camelia V Stan Material properties under high pressure, temperature, and strain are affected by the presence of impurities and defects, leading to changes in compressibility, strength, phase transition pressure, etc. To investigate some of these effects, we developed a method for implanting He ion gas bubbles throughout metal samples. This allows us to modify the metal starting impurity and introduce a large number of dislocation pinning sites without a significant change in microstructure. It is expected that doping will lead to material hardening, although the amount is predicted to depend on He bubble density and size. |
Tuesday, July 12, 2022 4:30PM - 4:45PM |
M05.00002: Diffraction Microscopes to Capture Shock-Induced Plasticity Leora E Dresselhaus-Marais, Henning F Poulsen, Kristoffer Haldrup, Marylesa Howard, Youssef Marzouk, Grethe Winther, Robert E Rudd, Jon H Eggert, Cara Vennari, Matthew H Seaberg, Tim van Driel, Kento Katagiri, Dimitri Khaghani, Norimasa Ozaki, Bernard Kozioziemski, Nicolas Bertin The microscopic origins of how plastic failure starts during shock waves is poorly understood, especially at the atomic scale. Limited techniques can measure the ultrafast and apparently stochastic dynamics required to uniquely describe how localized shear, hotspots and stresses can drive the elastic compression at 108 strain rates to induce kinetically dominated plasticity. My group is developing ultrafast X-ray microscopes with crystallographic contrast to measure plasticity across length- and time-scales. Using X-ray topography and dark-field X-ray microscopy, we collect images along the X-ray diffracted beam (i.e. Diffraction Contrast Microscopy, DCM) that resolve the long-range strain and misorientation fields that emanate from defect cores that project onto that crystallographic plane. In this way, we have been able to resolve the dynamics of dislocation patterning, the evolution of dislocation densities, and discrete dislocation avalanches. In this talk, I will introduce our optical, analytical, and theory framework for DCM in dynamic compression. I will describe our optical developments at XFELs that allow us to image shock mechanics with 2-0.15 μm resolution across hundreds of micrometers. I will then discuss the computer-vision tools we have developed to quantify the information about specific types of defect structures in our images, using simulations we have developed to predict DCM images for DDD-predicted defect structures. With this framework, I will show how our new tools are starting to shed light into shock-induced plasticity and strength in diamond – with experiments we performed at the Linac Coherent Light Source. Our new approach holds key opportunities to map out the potential energy landscape of the kinetically dominated plasticity observed in shock physics. |
Tuesday, July 12, 2022 4:45PM - 5:00PM |
M05.00003: Modelling plasticity in shock compressed Ta using CPFEM simulations David McGonegle, Philip Avraam, Simon Case, Andrew Comley, Emma Floyd, John Foster, Steve Rothman, James Turner, Patrick Heighway, Justin Wark, Christopher Wehrenberg Modelling plasticity in laser shock experiments presents a major scientific challenge, owing to the high pressures that can be generated and the large strain rates and dislocation densities that can occur. While great progress has been made with both molecular dynamics (MD) and hydrocode simulations, difficulties remain to accurately model dynamic compression at the scales of typical laser experiments, while capturing the physics occurring at the lattice level. We present a dislocation dynamics based crystal plasticity finite element model (CPFEM) to simulate dynamic compression in Ta. Using this approach, we can generate synthetic X-ray diffraction patterns, which can be compared to experimental data. By introducing a homogenous nucleation term, we are able to reproduce the grain rotation behaviour in shock compressed [110] fibre textured Ta found via an in situ femtosecond diffraction experiment performed at LCLS by Wehrenberg et al [1]. UK Ministry of Defence © Crown Owned Copyright 2022/AWE. |
Tuesday, July 12, 2022 5:00PM - 5:15PM |
M05.00004: Effect of impedance mismatch on flier plate impact response of metal laminates Liya Semenchenko, Daniel Martinez, David R Jones, Saryu J Fensin, Michael J Demkowicz We use experiments and modeling to investigate the effect of elastic impedance mismatch on the response of layered metal composites to flier plate impact. We choose Cu/Ta and Cu/Nb laminates as model materials for their high and low impedance contrast, respectively, while many other properties (flow stress contrast, lattice misfit, etc.) are comparable. Using elastic finite element modeling, we predict that the minimum impact velocity needed to initiate spall depends on impedance contrast, with the critical velocity being lower in Cu/Ta than in Cu/Nb. We process samples by accumulated roll bonding (ARB) and examine their dynamic failure using flier plate testing. This investigation sheds light on the role of impedance contrast in shock propagation and attenuation and in the resulting failure mechanisms. |
Tuesday, July 12, 2022 5:15PM - 5:30PM |
M05.00005: Multiphase extension of plasticity model for high energy density conditions Damian C Swift, Kazem Alidoost, Ryan Austin, Thomas Lockard, Sebastien Hamel, Christine J Wu, John E Klepeis, Philip A Sterne, James M McNaney We recently demonstrated that continuum-level plasticity can be described well for polycrystalline materials in the high energy density (HED) regime, using a single dislocation density and single mobility mechanism calibrated from electronic structure theory, with a single empirical parameter related to the Peierls barrier. We used the atom-in-jellium model for efficiency and wide-ranging predictions, but this model is restricted to elements, is relatively inaccurate at low pressures, and cannot account for polymorphism. Here we extend the calibration of the plasticity model to multiple phases, using multi-ion electronic structure calculations that are more accurate at low pressure and are not limited to elements. A separate calibration of the Peierls barrier parameter is needed for each phase. We demonstrate the calibration and predicted strength behavior for several materials of current interest in HED studies. |
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