Nanostructured Materials in Extreme Environments: Modeling and Simulation
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS Structural Materials Division, TMS: Nanomechanical Materials Behavior Committee, TMS: Advanced Characterization, Testing, and Simulation Committee, TMS: Mechanical Behavior of Materials Committee, TMS: Nuclear Materials Committee
Program Organizers: Haiming Wen, Missouri University of Science and Technology; Nan Li, Los Alamos National Laboratory; Youxing Chen, University of North Carolina Charlotte; Yue Fan, University of Michigan; Niaz Abdolrahim, University of Rochester; Khalid Hattar, University of Tennessee Knoxville; Ruslan Valiev, UFA State Aviation Technical University; Zhaoping Lu, University of Science and Technology Beijing
Thursday 8:30 AM
March 23, 2023
Room: Aqua 303
Location: Hilton
Session Chair: Yue Fan, University of Michigan
8:30 AM Invited
Exploring the Shear Localization in Metallic Nanolayered Composites via Atomistic Simulations: Caizhi Zhou1; Shujing Dong1; 1University of South Carolina
Metallic nanolayered composite (MNC) is a special type of composite material containing alternate layers of metals with layer thicknesses at nanometer scales. Due to their unique structure, great wear resistance, and improved radiation damage tolerance, they have attracted a lot of attention in recent years. However, their potential applications are limited by the formation of shear bands (SB) in compression or early fractures in tension. The present work explores the effects of layer thickness and crystal structure on the shear band formation in FCC/FCC and FCC/BCC MNCs with flat interfaces via molecular dynamics simulations. We analyze the configurations of dislocation structures, atomic separation distances of nearest neighbors, and von Mises shear strain distributions in the deformed samples with various layers thicknesses. Our results reveal that shear bands in MNCs form not only based on layer thicknesses and crystal structures, but also on the stacking fault energies of each phase.
8:55 AM Invited
The Role of Chemical Short-range Order on Defects Migration and Evolution in Multi-principal Element Alloys: Bin Xing1; Xinyi Wang1; Penghui Cao1; 1University of California, Irvine
Multi-principal element alloys with concentrated solid solutions are conceived to possess a rugged atomic and energy landscape in which defects motion necessarily proceeds to accommodate external thermomechanical stimuli. Fundamental questions remain as to how rough the energy landscape is and to what extent it can be influenced by the local ordering of the constituent elements. In this presentation, we will show that, in the presence of chemical short-range orders, vacancy diffusions considerably slow down, and the corresponding trajectories are localized. Concerning dislocation, the potential energy landscape governing dislocation motion reveals a hierarchical and multilevel structure with a collection of small basins nested in large metabasin. By introducing chemical short-range order, the energy landscape is smoothed but skewed to different degrees that balance the predominated mechanisms.
9:20 AM
Shock Compression of Nanocrystalline Boron Carbide from Deep Learning Molecular Dynamics Simulations: Qi An1; Jun Li1; 1Iowa State University
Understanding the dynamic behaviors of strong ceramics under shock compression is critical for their applications in extreme environments. Here, we develop an accurate machine learning force field (ML-FF) for superhard B4C by training deep neutral network using quantum mechanics simulations. Then we apply this ML-FF to examine the shock response and associated deformation mechanisms of nanocrystalline boron carbide (n-B4C) using large-scale non-equilibrium molecular dynamics simulations. The simulation results suggest that the grain boundary (GB) sliding and amorphization are responsible for the propagation of quasiplastic waves above its Hugoniot elastic limit. At high shock strength, the disintegrated icosahedra initiating from GBs propagate towards internal grains, causing the intragranular amorphous band formation. Our simulation results on shock Hugoniot agree very well with previous experiments. This study explains the shock-induced quasiplastic behaviors of nanocrystalline B4C, providing significant insight into assessing the deformation and damage of nanocrystalline ceramics under shock loading.
9:40 AM
Multi-scale Framework to Simulate the Long-term
Diffusion Radiation-induced Defects in Nano-crystalline Materials: Mohamed Hendy1; Okan Orhan1; Mauricio Ponga1; 1The University of British Columbia
Materials subjected to radiation environments experience a large spectrum of microstructural changes, impacting the mechanical properties of these materials over time. The processes involved in radiation-induced damage can span multiple length and time scales and are thus inherently multiscale and hierarchical. The initial damage occurs in the time span of picoseconds while the diffusion of the induced defects especially vacancies occur in the range of seconds, days and years which is beyond the capabilities of the classical molecular dynamics (MD) models. This requires the development of multi-scales models capable of capturing the phenomenon of interest at different time scales. This work presents a multiscale and multiphysics framework to investigate the radiation-induced damage in nano-crystalline materials. The framework combines two methodologies, including molecular dynamics simulations with electronic effects and long-term atomistic diffusion simulations in nano-crystalline materials. Using this framework, we investigated nano-crystalline materials' self-healing behaviour under radiation events.
10:00 AM Break
10:20 AM
Coarsening Kinetics in Surface-doped Nanoporous Metals: Luis Granadillo1; Ian McCue1; 1Northwestern University
Due to nanometer-scale features and high surface areas, nanoporous metals have the potential to be extremely radiation tolerant. However, these materials have intrinsically metastable morphologies and will degrade via coarsening during service. One potential mitigation strategy is to introduce impurities on the metal surface that inhibit diffusional transport – analogous to Zener pinning. While there have been a few instances of utilizing this strategy to improve morphological stability, there are no guiding principles regarding what fraction of impurities are required. To elucidate the relationship between impurity concentration and coarsening rate, we investigated the impact of trace surface dopants on the kinetics of coarsening in a nanoporous metal via kinetic Monte Carlo simulations. By applying kinetic analysis methods, we determined how the coarsening rate and rate-limiting site density was impacted by trace impurities. Insights from this work will have a measurable impact on the effort to develop morphologically stable nanostructure materials.
10:40 AM
The Role of Grain Boundaries in the Morphological Instabilities of Nanoscale Geometries: Omar Hussein1; Keith Coffman2; Khalid Hattar3; Eric Lang3; Shen Dillon4; Fadi Abdeljawad1; 1Clemson University; 2University of Illinois Urbana-Champaign; 3Sandia National Laboratories; 4University of California, Irvine
Recent advances in high-precision manufacturing techniques have enabled the fabrication of materials with nanoscale features, such as nanolattices and nanoporous structures. However, the microstructural stability of such morphologies under high-temperature environments is not well understood. Using theoretical, experimental, and computational studies, we examine the stability of nanostructured morphologies. Our in-situ annealing studies of polycrystalline alumina rods demonstrate a pinch-off instability in which the rod breaks up into spatially isolated domains, a phenomenon reminiscent of the Plateau-Rayleigh instability in liquids. We develop a theoretical model to investigate the impact of grain boundaries (GBs) on the morphological instabilities of nanoscale rods. Our analysis shows that GBs play a destabilizing role in which the critical wavelength for the instability decreases with increasing the GB energy. We complement our theoretical model with phase field simulations, which reveal that the time to pinch-off decreases with increasing the GB energy.
11:00 AM
A Grain Boundary Solute Drag in Regular Solution Alloys: Malek Alkayyali1; Fadi Abdeljawad1; 1Clemson University
The interaction of elemental species with grain boundaries (GBs) plays an important role in a wide range of materials phenomena. Recently, GB solute segregation has been experimentally shown to mitigate grain coarsening in nanocrystalline alloys. However, most studies are focused on the thermodynamic aspect of solute segregation, and the role of solute drag remains poorly understood. Herein, we present a solute drag model of regular solution alloys that accounts at a phenomenological level for the GB structure and its influence on segregation profiles. Further, the model incorporates solute-solute interactions in both the bulk and GBs. Our analysis reveals that solute drag is greatly influenced by the spatial concentration profile across the GB region. For example, multilayer segregation results in larger solute drag compared to the monolayer case. A universal GB solute drag-velocity relation is proposed that provides a robust fit for alloys with various chemical interactions and nominal compositions.