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 Z01: Phase Transition and Kinetics ModelingRecordings Available
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Chair: William Anderson, Los Alamos Natl Lab Room: Anaheim Marriott Platinum 5 |
Friday, July 15, 2022 11:00AM - 11:15AM |
Z01.00001: A model for deformation twinning in Tantalum under shock coupled with crystal plasticity Nicolas Bruzy, Christophe Denoual A finite strain phase field model for phase changes is derived to investigate the competition between <112> twinning and plastic activity during the rapid compression of Tantalum. The description of phase transformations relies on the Phase Field - Reaction Pathways formalism [1]. Transformation paths up to any target level are generated so that phenomena such as retwinning are reproduced. A crystal plasticity model is further embedded at each variant. The model is polyphase in the sense that the individual plastic behaviour of each transformation variant is taken into account. To reach finer scales in the description of the mechanical behavior, the chosen crystal plasticity model uses dislocation densities as internal variables. The proposed coupling between plasticity and phase transition takes into account two levels of inheritance: global inheritance through the weighting of the plastic contributions of all variants, and local inheritance through an ad hoc dislocation inheritance model. Simulations are performed using a 3D total Lagrangian code with an element-free Galerkin least-squares formulation. Computations results evidence strong correlations between microstructural evolutions and the local repartition of defects. |
Friday, July 15, 2022 11:15AM - 11:30AM |
Z01.00002: A model for the solid–liquid interfacial free energy at high pressures Dane M Sterbentz, Philip C Myint, Jean-Pierre Delplanque, Yue Hao, Justin L Brown, Brian S Stoltzfus, Jonathan L Belof For the ubiquitous process of solidification, the solid–liquid interfacial free energy is necessary for modeling the phase-transition kinetics using classical nucleation theory (CNT)-based methods, since it dictates the height of the nucleation energy barrier. However, interfacial free-energy models in prior literature tend to make restrictive approximations (such as being at or near the melt temperature and/or at ambient pressures), which may break down in dynamic-compression experiments where metastable liquids are deeply undercooled or overpressurized before solidifying. We derive a solid–liquid interfacial free-energy model for such high-pressure conditions that is applicable to both metallic and nonmetallic systems and allows an examination of the structure and thickness of the interface. We apply our interfacial free energy model to CNT-based kinetics simulations of dynamic-compression experiments that involve the liquid water–ice VII phase transition and find good agreement with only minor empirical fitting. |
Friday, July 15, 2022 11:30AM - 11:45AM |
Z01.00003: An efficient method for phase-behavior calculations and its application to modeling phase-transition kinetics Yue Hao, Philip C Myint, Jesse E Pino, Jonathan L Belof Evaluation of multiphase thermodynamic properties is a critical component for simulating the kinetics of phase transitions at high pressures and temperatures under dynamic compression. It requires iterative equation-of-state (EOS) calculations to determine pressure, temperature and phase volumes and energies given the total volume, internal energy, and phase fractions. The phase-transition kinetics model reported by Myint et al. (2020) employs a semi-analytical approach to map the general EOS onto an analytically inversible (AI) EOS and obtain the pressure and temperature analytically. Here, we develop an alternative approach based on the Newton-Raphson (NR) method. The NR-EOS computation is coupled with our phase-transition-kinetics code to simulate solidification processes of water and gallium under dynamic compression. We find that the NR-EOS approach exhibits faster solution convergence than the AI-EOS method, especially for modeling of solidification kinetics in large, multidimensional systems. If time permits, other numerical considerations (timestep controls, numerical stability for ALE problems) will be presented as well. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. |
Friday, July 15, 2022 11:45AM - 12:00PM |
Z01.00004: Liquid-Vapor Critical Point and Coexistence Boundary of Platinum From Ab Initio Simulation Meghan Lentz, Joshua P Townsend, Kyle R Cochrane Platinum (Pt) is a highly unreactive transition metal with a high melting point. Alongside its everyday uses, Pt’s properties make it suitable for use in harsh environments such as high temperature experiments. Previous literature [High Temp.- High Press., V. 46, No. 4-5, p. 367 (2017); J. Phys. Chem. B 2016, 120, 23, 5255–5261] have reported a wide range of values for the critical properties of Pt. Here we present the liquid-vapor critical point and the coexistence boundary of Pt, comparing these to previously reported results, both theoretical and experimental. The critical point is estimated from an equation of state fit to molecular dynamic simulation data. We also present the high-temperature electrical conductivity and optical properties of Pt. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525 |
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