Computational Thermodynamics and Kinetics: Kinetics and Transport
Sponsored by: TMS Functional Materials Division, TMS Materials Processing and Manufacturing Division, TMS: Chemistry and Physics of Materials Committee, TMS: Computational Materials Science and Engineering Committee, TMS: Integrated Computational Materials Engineering Committee, TMS: Solidification Committee
Program Organizers: Hesam Askari, University Of Rochester; Damien Tourret, IMDEA Materials Institute; Eva Zarkadoula, Oak Ridge National Laboratory; Enrique Martinez Saez, Clemson University; Frederic Soisson, Cea Saclay; Fadi Abdeljawad, Lehigh University; Ziyong Hou, Chongqing University
Monday 8:30 AM
March 20, 2023
Room: 26A
Location: SDCC
Session Chair: Theresa Davey, Bangor University; Eva Zarkadoula, Oak Ridge National Laboratory
8:30 AM Invited
Interplay between Thermodynamics and Kinetics in Solid-state Synthesis: Katsuyo Thornton1; 1University of Michigan
Solid-state synthesis is widely used to produce a variety of multicomponent compounds. In particular, solid-state metathesis has recently been demonstrated for synthesis of compounds that are difficult to produce by other synthesis routes. However, such a process involves at least two anion species and two cation species, leading to a highly complex thermodynamic landscape as well as kinetics. Therefore, the fundamental understanding behind the metathesis reaction is still lacking. Phase field modeling is uniquely suited to elucidate such processes at the microstructure scale because it accounts for the interplay between the thermodynamics and kinetics. In this work, a phase field model is developed and applied to solid-state synthesis to gain insights into the process, including how the connectivities between precursor phases affect the kinetics. This work was supported by EFRC GENESIS: A Next Generation Synthesis Center funded by the U.S. Department of Energy under Award No. DE-SC0019212.
9:00 AM
Characterization of Grain Boundary Phase Transformations: Ian Winter1; Robert Rudd2; Tomas Oppelstrup2; Timofey Frolov2; 1Sandia National Laboratories; 2Lawrence Livermore National Laboratory
Grain boundaries greatly influence many properties of engineering materials. Accurate prediction of their structure and possible transitions using atomistic modeling are important for strategies that aim to improve properties of materials. Recent years have seen a rapid growth of evidence suggesting that materials interfaces are capable of first-order structural transformations in which the interface properties undergo discontinuous changes and have raised fundamental questions concerning the atomic structures and kinetic properties of these interface phases. In this work, we model grain boundary phase transformations in crystalline systems. We introduce a new method to characterize the dislocation content of grain boundaries, which can enable studies of grain boundary phase transformation kinetics. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525 (SAND2022-1056 A).
9:20 AM
Kinetic Monte Carlo Simulations of BCC Crystal Surfaces with Applications to Chromium, Titanium, and Nitinol: Pheobe Appel1; Divya Sharma1; Paulette Clancy1; Jonah Erlebacher1; 1Johns Hopkins University
There is a subtle but critical challenge in using mesoscale (10-100 nm) kinetic Monte Carlo (KMC) to simulate surface diffusion in body-centered cubic (BCC) crystals, namely, that the common “bond breaking model” in which the activation barrier for diffusion is proportional to the local coordination, cannot be applied. This is because basic surface migration events require second near-neighbor jumps, e.g., adatoms in (001) terraces jumping from body center to body center. To account for the complex mechanisms of surface diffusion found on BCC surfaces, we developed heuristic models for site-dependent surface migration that includes both first- and second-near neighbor information, and that were validated by DFT calculations. The simulation methodology was applied to chromium, titanium, and Nitinol and used to simulate the kinetic evolution of nanoparticles of these materials toward their Wulff shapes.
9:40 AM
Accelerating Off-lattice Kinetic Monte Carlo Simulations to Predict Hydrogen Vacancy-cluster Interactions in α–Fe: Conor Williams1; Enrique Galindo-Nava2; 1University of Cambridge; 2University College London
We present an enhanced off-lattice kinetic Monte Carlo (KMC) model, incorporating a new method for tolerant classification of atomistic local-environments, capable of simulating vacancy-hydrogen complexes at atomic resolution and hydrogen embrittlement timescales. Our classification method is invariant under Euclidean-transformations and permutation of identical atoms and equivalence is controlled by a single tolerance parameter. We apply our model to study the trapping/detrapping of hydrogen from up to five-vacancy clusters and simultaneously the effect hydrogen has on the diffusivity of these clusters. We predict the diffusion pathways of clusters/complexes without a priori assumptions of their mechanisms. We detail the hydrogen-induced changes in the clusters' diffusion mechanisms and find evidence that, in contrast to mono-vacancies, the introduction of hydrogen to larger clusters can increase their diffusivity. Finally, we compute the trapping atmosphere of meta-stable states surrounding non-point traps, opening new avenues to better understand and predict hydrogen embrittlement in complex alloys.
10:00 AM Break
10:20 AM
Microscopic View of Heat Capacity of Matter: Jaeyun Moon1; Takeshi Egami2; 1Oak Ridge National Laboratory; 2University of Tennessee, Knoxville
In contrast to thermodynamic properties of solids and gases that are well-characterized by phonon quasi-particles and real particles, respectively, our microscopic understanding of thermodynamics in liquids is lacking due to strong atomic interactions and lack of symmetry. Recent prior works have initiated efforts to describe heat capacity of liquids based on phonon quasi-particles similar to that of solids but often rely on free fitting parameters and questionable assumptions. In this work, we perform instantaneous normal mode and velocity autocorrelation analysis on single element systems under various conditions up to 10^8 K and 1 TPa. Our results suggest that heat capacity of liquids can be described by a combination of both quasi-particles and real-particles, leading to a unified framework to describe heat capacity of all three phases of matter: solid, liquid, and gas.*Supported by the Department of Energy, Office of Science, Basic Energy Sciences,Materials Sciences and Engineering Division.
10:40 AM
Semi-empirical Approach for Analyzing the Microstructure-aware Effective Thermal Conductivity of Polycrystalline Materials: Younggil Song1; N. C. Du1; D.-X. Qu1; T. W. Heo1; 1Lawrence Livermore National Laboratory
Efficient evaluation of effective thermal conductivities (ETCs) of inhomogeneous materials is key for designing better performing materials for various applications, including hydrogen storage, thermal energy storage, and high-temperature industrial processes. In this presentation, we will report a novel semi-empirical model for ETCs of polycrystalline materials. Using the recently developed numerical approach based on the Fourier-spectral iterative-perturbation method, we generated extensive ETC data with varying microstructural parameters of porous binary mixture of materials. To capture microstructural impacts on ETCs, we propose a semi-empirical model incorporating diffuse-interface description for the material surface with two key control parameters. The proposed model reproduces characterized variabilities of ETCs in both simulations and experiments. The semi-empirical model provides an efficient tool to examine microstructure-dependent ETCs, which is necessary for identifying engineering guidance for practical materials. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
11:00 AM
A Phase Field Approach to Study Precipitate Migration under Temperature Gradient: Sandip Guin1; Soumya Bandyopadhyay2; Saswata Bhattacharya3; Rajdip Mukherjee4; 1Indian Institute of Technology, Kanpur/National Yang Ming Chiao Tung University; 2Indian Institute of Technology, Kanpur/Kookmin University; 3Indian Institute of Technology, Hyderabad; 4Indian Institute of Technology, Kanpur
Thermomigration is a phenomenon where atoms migrate under a temperature gradient. It has been a matter of interest to study the effect of thermomigration on microstructure evolution in the scientific community for the last few decades. In the present work, we rigorously explore the thermodynamics and kinetics of precipitates subjected to a thermal gradient using a novel phase-field approach. We systematically study the thermomigration behavior for single and multiple precipitate systems by varying the shape of the precipitates and inter-precipitate distance. We begin with an infinite strip-like precipitate with flat interfaces to avoid curvature effects. It allows us to validate our phase-field model to analytically obtained results. It is followed by a study on circular precipitates taking into account the impact of curvature. We observe that the precpitate migration velocity depends on the size of the precipitate. Further, our study on multi-precipitate systems elucidates the concurrentthermomigration and coarsening phenomena.
11:20 AM
First-principles Investigation of Alloying Element Migration and Intermetallic Phase Formation in a Cr-alloy Coated Zr-alloy Accident Tolerant Nuclear Fuel System: Theresa Davey1; Ying Chen1; 1Tohoku University
To improve the safety and lifetime of boiling water-type nuclear fission reactors, new accident tolerant fuels are under development where a Cr-alloy coating is applied to the conventional Zr-alloy nuclear fuel cladding. However, an undesirable brittle intermetallic layer of ZrCr2 may form between the Cr-based coating and the Zr-based alloy, damaging the integrity of the fuel system. Furthermore, diffusion of chromium, zirconium, and other alloying elements occurs in each of the metallic layers, affecting the alloy properties. The thermodynamics of the various interfaces and layers formed are considered using first-principles calculations to predict atomic migration and intermetallic phase formation within the system. Based on this data, candidate alloying elements for the Cr-alloy or Zr-alloy are proposed that may reduce the formation of the ZrCr2 intermetallic phases, eliminate significant volume changes that may cause microcracking, or that may improve the properties of the cladding system as a whole.