Computational and Modeling Challenges in Metals and Alloys for Extreme Environments: High Strain Rates and Irradiation Effects
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS Structural Materials Division, TMS: Computational Materials Science and Engineering Committee, TMS: Integrated Computational Materials Engineering Committee
Program Organizers: Jean-Briac le Graverend, Texas A&M University; Jaafar El-Awady, Johns Hopkins University; Giacomo Po, University of Miami; Beñat Gurrutxaga-Lerma, University of Birmingham

Monday 2:00 PM
March 15, 2021
Room: RM 19
Location: TMS2021 Virtual

Session Chair: Giacomo Po, University of Miami; Laurent Capolungo, Los Alamos National Lab

2:00 PM
Investigation of Role of Interface Microstructure on the Shock Compression and Spall Failure Behavior of Nanoscale Cu/Ta Multiphase Metallic Materials: Marco Echeverria¹; Avinash Dongare¹; ¹University of Connecticut
    The design of multiphase metallic materials for impact tolerant applications relies upon a fundamental understanding of the evolution of deformation-induced defects (e.g. dislocations and twins) and their transport through inhomogeneities. The role of interface microstructure (e.g. size, structure, distribution of interfaces) has become a vital topic to investigate due to the mechanisms of defect evolution and their interactions with interfaces to nucleate voids leading to spall failure. Large scale molecular dynamics simulations are carried out to investigate the shock-induced evolution of defects, specifically the twinning/detwinning behavior observed in these materials due to the presence of interfaces. The simulations comprise Cu/Ta multilayered alloys with imposed orientation relations at the interfaces, as well as microstructures with nanometric intermediate layers to mimic the clustering of Cu or Ta in their opposites. The links between void evolution and defect transport through interfaces and the subsequent spall failure are presented.

2:20 PM
Modeling of Laser Interactions with BCC Metals Using a Hybrid Atomistic-continuum Approach: Ching Chen¹; Avanish Mishra¹; Sergey Galitskiy¹; Avinash Dongare¹; ¹University of Connecticut
    The modeling of interaction of metallic materials with lasers requires an accurate description of absorption of the laser energy by electrons, heat generation/transfer and the energy dissipation mechanisms that can result in ablation, spallation, melting and shock compression behavior. Such a capability is available through a hybrid method that combines the dynamics atoms modeling using classical molecular dynamics (MD) with a continuum two-temperature model (TTM) to incorporate the energy absorption by electrons and the heating of the lattice when a metal interacts with a laser. The MD-TTM framework is extended to Ta, Fe and Mo systems wherein the electronic-temperature-dependent electron heat capacities, electron thermal conductivities, and electron-phonon coupling factors are parameterized using first principles simulations. The talk will discuss the framework of the MD-TTM simulations, the parameterization of the TTM and the capabilities to model interaction of femtosecond lasers with microstructures of Ta, Fe and Mo systems will be demonstrated.

2:40 PM
Mesoscale Modeling of Deformation Behavior of Fe-based Microstructures at High Strain Rates and under Shock Loading Conditions: Ke Ma¹; Avinash Dongare¹; ¹University of Connecticut
    A novel mesoscale modeling method called quasi-coarse-grained dynamics (QCGD) is used to model the deformation behavior of polycrystalline and deformation-processed ultrafine-grained (UFG) iron microstructures. The QCGD simulations extend the capability of molecular dynamics simulations to the mesoscales by reducing the number of atoms being modeled in an atomic scale microstructure using representative atoms and scaled interatomic potentials. QCGD simulations are carried out to investigate the role of microstructure (with a grain size of up to a few microns) and pre-existing distributions of heterogeneities (dislocations, voids) to mimic deformation processed microstructures on the mesoscale mechanics of these materials during high rate compression and tension. The framework and capabilities of the QCGD simulations, the microstructural evolution (deformation twinning and phase transformation behavior) during high rate deformation behavior of Fe microstructures will be presented. The role of loading conditions and heterogeneities on thresholds for twinning/de-twinning and phase transformation behavior will be discussed.

3:00 PM
The Microscopic Structure of a Heavily Irradiated Metal: Peter Derlet¹; Sergei Dudarev²; ¹Paul Scherrer Insitute; ²UKAEA CCFE
    Using atomistic simulation, we study the material response of the steady-state micro-structure produced under high-dosage irradiation conditions. Such a micro-structure contains an extended dislocation network embedded in a largely homogeneous population of vacancies. We find that local perturbations to such a structure can result in a non-local response, reflecting a steady-state fluctuation spectrum driven by internal stresses that accumulate the stochastic generation of point defects. Both BCC Fe and W are considered up to canonical DPA values of O(20).