Computational Thermodynamics and Kinetics: Phase Stability and Diffusion Kinetics
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
Tuesday 2:30 PM
March 21, 2023
Room: 26A
Location: SDCC
Session Chair: Sara Kadkhodaei, University Of Illinois Chicago; Frederic Soisson, Cea Saclay
2:30 PM Invited
A New First Principles Approach for Modeling Diffusion Kinetics in Structurally Unstable Phases: Sara Kadkhodaei1; Seyyedfaridoddin Fattahpour1; 1University of Illinois Chicago
Numerous materials of technological importance feature high-temperature phases that exhibit phonon instabilities. Leading examples include shape-memory alloys, ferroelectric oxides, refractory oxides, and some metal hydrides. I will introduce a new model for diffusion barrier calculation in these phases. Our model efficiently explores the system’s diffusive transition path using a saddle-point search scheme based on a Gaussian process regression of the temperature-dependent energy surface. Our model simultaneously samples the temperature-dependent energy surface and converges the system to the saddle point. Our method provides a useful alternative to methods such as molecular dynamics, which directly simulate diffusive hops. I present the application of this model for some metals and oxides. References S. Kadkhodaei and A. Davariashtiyani, Phys. Rev. Materials 4, 043802, 2020Fattahpour, S and Davariashtiyani, A and Kadkhodaei, S. Phys. Rev. Materials 6, 023803, 2022
3:00 PM
Modeling of Location-Specific Microstructures in Additive Manufacturing of Metallic Alloys by Combining Nonequilibrium Phase-Field and Fast Thermal Models: Jose Mancias1; Robert Saunders2; Damien Tourret3; Raymundo Arroyave1; 1Texas A&M University; 2U.S. Naval Research Laboratory; 3IMDEA Materials Institute
Additively manufactured metallic microstructures depend on the alloy and processing parameters as well as the geometry of the printed part. In this study, we aim to capture location-specific microstructural heterogeneities by combining a geometry-aware thermal model, the NRL Enriched Analytical Solution Method (NEASM), [Additive Manufacturing 25 (2019) 437] with a phase-field (PF) approach for rapid solidification [Computational Materials Science 188 (2021) 110184]. The PF model is used to generate microstructures in various regions (e.g. in the presence of corner, edges, etc.) of the part using thermal conditions provided by the NEASM. The PF model is based on the relaxation of the partition coefficient at the solid-liquid interface (which relaxes the equal diffusion potential condition of conventional phase field models) and is GPU parallelized in Julia. By combining the PF and NEASM methods, the prediction of location-specific microstructure heterogeneities due to part geometry in powder-bed fusion processes is possible.
3:20 PM
Modelling the Kinetics of Phase Transformations with Non-conservative Point Defects: Frederic Soisson1; 1CEA Saclay
In metallic alloys, diffusive phase transformations occur through thermally activated jumps of point defects. Kinetic pathways and microstructure evolutions therefore depend on the point defect jump frequencies, which depend on the local atomic environment; but also on the point defect concentration, which evolves during the transformation. We present a new atomic Kinetic Monte Carlo method that explicitly takes into account the creation and annihilation of point defects at source and sink sites. It allows the simulation of phase transformation kinetics when the point defects concentration evolves with the microstructure of the system, but remains at a thermodynamic equilibrium value. The method can also be used in far from equilibrium situations, e.g. during rapid quenching or under irradiation. We present some applications of this method to the ordering of Fe-Ni alloys during thermal ageing, and to the segregation and phase separation in Fe-Cr alloys under irradiation.
3:40 PM
Exploring Short-range Order and Phase Stability of CrCoNi Using Machine Learning Potentials: Sheuly Ghosh1; Vadim Sotskov2; Alexander Shapeev2; Joerg Neugebauer1; Fritz Koermann1; 1Max-Planck-Institut für Eisenforschung GmbH; 2Skolkovo Institute of Science and Technology
Solid solutions of multicomponent alloys are often assumed to be ideally random. However, short-range-order, which is challenging to quantify by experiments, is known to affect the phase stability and mechanical properties of these alloys. It is therefore important to quantify the degree of local chemical ordering as function of temperature and its chemical nature. In the present work, we have investigated short-range-order and its impact on phase stability in CrCoNi medium-entropy alloy. This alloy is known for its cryogenic damage tolerance and general mechanical superiority. For this purpose, we have employed a recently proposed computationally efficient on-lattice machine-learning interatomic potential called low-rank potentials. These potentials, which fully account for atomic relaxations, are capable of accurately representing interactions in a system with many chemical components and are used in subsequent Monte Carlo simulations. The computed short-range-order parameters and observed ordering are discussed in view of recent simulation and experimental works.
4:00 PM Break
4:20 PM Invited
Understanding the Effect of Crystal Anisotropy on Grain Growth, Texturing, and Transport via the Orthorhombic Alpha-uranium System: Andrea Jokisaari1; Benjamin Beeler2; Khadija Mahbuba2; Yuhao Wang3; 1Idaho National Laboratory; 2North Carolina State University; 3University of Michigan
The alpha phase of uranium exhibits the orthorhombic crystal structure, resulting in significant physical property anisotropy. These complex properties make the material challenging to work with in engineering settings but provide a rich arena to investigate the fundamental, multi-scale effects of anisotropy on physical behaviors such as grain growth and microstructure evolution under irradiation. We apply molecular dynamics and phase field modeling to study mass transport and grain growth in alpha-uranium. We characterize the mobilities of crystalline defects and the interfacial energy, and we find that the grain boundary energy is highly variable depending on the interface structure and that the relative rates of defect transport change with temperature. We also find that anisotropic thermal expansion has a significant impact on grain growth kinetics and texture development. Our results are used to explain experimental observations and to provide a basis for further hypotheses into the complex physical behavior of alpha-uranium.
4:50 PM
Phase-Field Modeling of Iron Oxide Reduction with Hydrogen: Dierk Raabe1; Yang Bai1; Jaber Rezaei Mianroodi1; Alisson Kwiatkowski da Silva1; Bob Svendsen1; Xuyang Zhou1; 1Max-Planck Institute
We present a chemo-mechanically coupled phase-field model to study the interplay between phase transformation, chemical reactions, diffusion, large elasto-plastic deformation and microstructure evolution in hydrogen-based direct reduction of iron oxide, as a basis for green steel making.Simulations help to understand the roles of phase transformation, plastic deformation, porosity, water removal and fracture on kinetics and metallization.
5:10 PM Invited
Diffusion and Chemo-mechanics of Li-metal Alloys: Anton Van der Ven1; Sesha Behara1; 1University of California, Santa Barbara
Commercial Li-ion batteries rely on intercalation reactions within their electrodes. However, the desire to increase energy density is pushing the field away from graphite intercalation compounds to higher capacity anodes. One approach is to rely on metallic Li and on alloying reactions at the anode electrode. This talk will describe the results of first-principles statistical mechanics studies of phase stability and kinetics of Li-metal alloys. Li forms a rich variety of intermetallic compounds with different metals from the periodic table. Many of the intermetallic compounds can be viewed as unique orderings of Li and metal on the sites of simple parent crystal structures. Several Li-intermetallic compounds are surprisingly tolerant to anti-site defects and vacancy formation, an important property to enable rapid interdiffusion between Li and metallic alloying elements. Structural pathways that underly martensitic transformations are also widespread amongst Li-intermetallic compounds leading to intriguing chemo-mechanical couplings.