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 W03: Molecular Dynamics Simulations of MetalsRecordings Available
|
Hide Abstracts |
Chair: Matthew Kroonblawd, Lawrence Livermore Natl Lab Room: Anaheim Marriott Platinum 1 |
Thursday, July 14, 2022 4:00PM - 4:15PM |
W03.00001: Molecular Dynamics of High Pressure Tin Phases I: Strength and Deformation Evaluation of Empirical Potentials J Matthew D Lane, Mary Alice Cusentino, Ben Nebgen, Kipton M Barros, John D Shimanek, Alice Allen, Aidan P Thompson, Saryu J Fensin Atomistic modeling of materials under high pressure shock and ramp conditions can provide information on deformation mechanisms under these extreme conditions. Molecular dynamics modeling of tin under these conditions is of particular interest in order to study the effects of phase transformation on high strain rate plasticity. |
Thursday, July 14, 2022 4:15PM - 4:30PM |
W03.00002: Molecular Dynamics of High Pressure Tin Phases II: Machine Learned Interatomic Potential Development Mary Alice, Ben Nebgen, Kipton M Barros, John D Shimanek, Alice Allen, Aidan P Thompson, Saryu J Fensin, J Matthew D Lane Atomistic modeling of materials under high pressure shock and ramp conditions can provide information on deformation mechanisms under these extreme conditions. Molecular dynamics modeling of tin under these conditions is of particular interest in order to study the effects of phase transformation on high strain rate plasticity. |
Thursday, July 14, 2022 4:30PM - 4:45PM |
W03.00003: A study about shock-induced spallation in mono- and nanocrystalline high-entropy alloys Daniel Thürmer, Nina Merkert (née Gunkelmann), Shiteng Zhao, Orlando R Deluigi, Camelia V Stan, Iyad A Alhafez, Herbert M Urbassek, Marc A Meyers, Eduardo M Bringa High-entropy alloys are highly attractive for future applications in the technical field thanks to their incredible potential regarding mechanical properties. Although they are increasingly sparking interest for future usage, their general understanding is not yet complete. To further understand high-entropy alloys and their capabilites, we studied the influence of shock-induced spallation on mono- and nanocrystalline high-entropy alloys with varying grain sizes. The monocrystalline sample shows high spall strength and was compared to experiments that also showed high spall strengths. The nanocrystalline high-entropy alloy samples also show high spall strength, but the spall strength is lower compared to the monocrystalline sample. While our monocrystalline high-entropy alloy shows an amorphous region giving rise to void nucleation and spall during loading, our nanocrystalline high-entropy alloy samples show a high amount of stacking faults, twins and dislocations during shock. These even persist during the release of the shock wave. This is in good agreement with earlier shock loading experiments using high power lasers where nanotwinning has been observed in the recovered samples. |
Thursday, July 14, 2022 4:45PM - 5:00PM |
W03.00004: Kinematics of plasticity-induced rotation during shock or ramp compression to extreme pressures Justin Wark, Patrick G Heighway When a metallic specimen is rapidly compressed via laser-plasma ablation, its underlying crystal structure must often rotate as it plastically deforms. There is growing interest in the dynamic compression community in exploiting x-ray diffraction measurements of lattice rotation to infer which combinations of plasticity mechanisms are operative in uniaxially shocked crystals, and thus inform materials science at extreme pressures and strain rates [see for example Wehrenberg et. al., Nature 550, 496-499 (2017)]. However, it is not widely appreciated that many existing models linking rotation to slip activity are fundamentally inapplicable to a planar shock-loading scenario. We have conducted molecular dynamics simulations of single crystals suffering true uniaxial strain, and have found that the Schmid and Taylor analyses frequently used in traditional materials science fail to predict the ensuing texture evolution. We propose a simple alternative framework that successfully recovers the observed rotation, and can further be used to correctly identify the active slip systems in the idealised cases of single and conjugate slip [Heighway and Wark, J. Appl. Phys. 129, 085109 (2021)]. |
Thursday, July 14, 2022 5:00PM - 5:15PM |
W03.00005: Combined Computational-Experimental Study of Shock Induced Plasticity in Tantalum Natan Karaev, Dan Mordehai, Eli Sarid, Roman Kositski, Vitaly Paris, Arnon Yosef-Hai The shock induced elastic-plastic transition in body-centered cubic (BCC) metals has been measured experimentally and displays a unique behavior of the Hugoniot elastic limit (HEL). Kositski and Mordehai [1] proposed that competition between dislocation nucleation and glide, which depend on initial microstructure, is responsible for this abnormality. To understand the HEL, both experiments and computations were performed: Experimentally, as-received and annealed Ta samples were shocked in a gas gun setup and their free surface velocities were measured. The differences in the HEL between the different samples are attributed to dislocation nucleation, thus one needs to quantify it. Dislocations are more likely to be nucleated from defects and thus the activation parameters for dislocation nucleation from grain boundaries were calculated: Molecular Dynamics (MD) simulations to study these processes in Ta bi-crystals were performed and analyzed in a range of temperatures. Finally, incorporation of the MD results in a multiscale model was examined. |
Thursday, July 14, 2022 5:15PM - 5:30PM |
W03.00006: Slip competition and rotation suppression in tantalum and copper during dynamic uniaxial compression Patrick G Heighway, Justin Wark When dynamically compressed via laser-plasma ablation, a metallic specimen will generally undergo changes to its crystallographic texture due to plasticity-induced rotation. The axis and the extent of the local rotation can provide hints about the combination of plasticity mechanisms activated by the rapid uniaxial compression, thus providing valuable information about the underlying dislocation kinetics that are operative under extreme loading conditions. We present molecular dynamics simulations of shock-induced lattice rotation in three model crystals whose behaviour has previously been characterised in dynamic-compression experiments: tantalum shocked along its [101] direction, and copper shocked along either [001] or [111]. Our simulations indicate that while tantalum loaded along [101] and copper loaded along [001] both show pronounced rotation due to asymmetric multiple slip, the orientation of copper shocked along [111] is stabilised by opposing rotations arising from competing, symmetrically equivalent slip systems. In all three cases, the sense of the reorientation predicted by the simulations is consistent with that measured experimentally using in situ x-ray diffraction. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700