Bulletin of the American Physical Society
21st Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 64, Number 8
Sunday–Friday, June 16–21, 2019; Portland, Oregon
Session S4: MS: Phase Transitions II |
Hide Abstracts |
Chair: Christopher Molek, AFRL Room: Pavilion West |
Thursday, June 20, 2019 11:00AM - 11:15AM |
S4.00001: ABSTRACT WITHDRAWN |
Thursday, June 20, 2019 11:15AM - 11:30AM |
S4.00002: Amorphization of covalently bonded solids under dynamic compression Shiteng Zhao, Eric Hahn, Christopher Wehrenberg, Hye-Sook Park, Bruce Remington, Marc Meyers In this investigation, we show pulsed laser-driven, shock-induced amorphization in four different covalently bonded solids, namely, silicon, germanium, boron carbide and silicon carbide. The critical threshold for the amorphization scales with the hardness of these materials, yielding B$_{\mathrm{4}}$C\textgreater SiC\textgreater Si\textgreater Ge. Post shock microstructural characterization was conducted to study the deformation/failure mechanism of these materials. The directional feature of the amorphous band suggests that shear stress play a crucial role triggering the crystalline-to-amorphous transition. Shear manifests itself in three possible ways: (1) it causes massive inelastic lattice displacement that can lead to the loss of long-range order; (2) it lowers the melting temperature of; (3) it causes localized heating which lead to localized thermal softening. Nanobeam electron diffraction provides an unprecedented spatial resolution to study the detailed microstructure of the shock-induced amorphous materials. The interfacial strain between the crystalline-amorphous interface will be discussed. [Preview Abstract] |
Thursday, June 20, 2019 11:30AM - 11:45AM |
S4.00003: First-principles molecular dynamics simulations of high-pressure phase diagram of carbon Kien Nguyen Cong, Jonathan Willman, Ashley Williams, Anatoly Belonoshko, Ivan Oleynik Although high-pressure phase diagram of carbon at extreme temperatures and pressures has been in the focus of intensive experimental and theoretical studies, there still exist outstanding problems including disagreement between theoretical predictions and experiment. We present results of first-principles molecular dynamics simulations of thermodynamic properties of carbon at high temperatures and pressures, which are performed with the goal of constructing an accurate phase diagram of carbon. To address the issue of accuracy and reliability, a relatively large number of atoms is used for calculation of melting transitions (melt curve) as a function of pressure. Accurate Gibbs free energies are calculated using temperature dependent effective potential method. We specifically focus on important region of phase diagram where diamond exhibits a negative melting line slope at pressures above 500 GPa. [Preview Abstract] |
Thursday, June 20, 2019 11:45AM - 12:00PM |
S4.00004: High-Pressure Shock Response and Phase Transition of Soda-Lime Glass Joshua E. Gorfain, C. Scott Alexander, Christopher T. Key The phase transition of crystalline and amorphous silica materials to a stishovite-like high-pressure phase has received considerable interest. While most work has focused on pure SiO$_{\mathrm{2}}$ glass (fused silica), studies identifying a similar high-pressure phase transformation in soda-lime glass have not been performed. Marked differences in the network structure and compressibility of soda-lime as compared to fused silica raise questions as to how a stishovite transition manifests in these glasses. In this work, plate impact experiments on soda-lime glass have been performed to \textasciitilde 110 GPa to measure the Hugoniot response at previously un-accessed pressures. Results of these tests supply evidence of a transition to a high-pressure polymorph under shock loading. A glass constitutive model is proposed to capture this newly found high-pressure response. Good agreement between time resolved measurements and simulation results from the CTH hydrocode with this model implemented are shown, along with additional insights into the apparent glass behavior. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525. [Preview Abstract] |
Thursday, June 20, 2019 12:00PM - 12:15PM |
S4.00005: Scale and rate dependence of phase transition pressure in CdS nanoparticles J. Matthew D. Lane, Jason P. Koski, Aidan P. Thompson, Ishan Srivastava, Gary S. Grest, Tommy Ao, Brian S. Stoltzfus, Kevin N. Austin, Hongyou Fan, Marcus D. Knudson, Dane Morgan Recent efforts to improve our predictive capability for modeling rate-dependent behavior at, or near, phase transition using molecular dynamics simulations will be described. Cadmium sulfide is a well-studied material which undergoes a solid-solid phase transition from wurtzite to rock salt structures between 3 and 9 GPa. Atomistic simulations are used to investigate the dominant transition mechanisms as a function of orientation, size and rate. The CdS solid-solid phase transition is studied, for both a bulk single crystal and for polymer-encapsulated spherical nanoparticles of various sizes. The transition kinetics, mapped to nanoparticle size and loading rate, will be discussed for particles of diameter 2 to 10 nm. Finally, we will briefly review the experimental effort to investigate this transition using X-ray diffraction on the Thor platform at Sandia. Supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA-0003525. [Preview Abstract] |
Thursday, June 20, 2019 12:15PM - 12:30PM |
S4.00006: Phase transition behavior of silicon nitride under shock loading and unloading process Nobuaki Kawai Shock wave profile measurements were performed on silicon nitride ceramics to investigate its shock-induced phase transition behavior. Experimental results clearly show the formation of the shock wave with multi-wave structure associated with the occurrence of elastic-plastic transition and phase transition under shock-loading process. The stress wave following the phase transition wave consists of ramp wave followed by steep shock wave. The formation of the ramp wave indicates the existence of non-crystalline intermediate phase between crystalline low pressure phase and crystalline high pressure phase. On the stress release from the shocked state which is compressed over phase transition point, release wave structure shows steep slope in the middle of release process indicating the occurrence of reverse transition. The stress ranges of the ramp compression in loading process and the steep release in unloading process are quite similar each other. The stress width of that region is about 10 GPa. This result indicates that the crystal structure of shocked silicon nitride become unstable in this stress region. The existence of this unstable phase region is considered to be caused by the sluggish nature of the phase transition mechanism of silicon nitride. [Preview Abstract] |
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