Computational Thermodynamics and Kinetics: Alloys, Design and Properties
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
Thursday 8:30 AM
March 23, 2023
Room: 26A
Location: SDCC
Session Chair: Joerg Neugebauer, Max-Planck-Institut; Giancarlo Trimarchi, Thermo-Calc Software Ab
8:30 AM Invited
Constructing Defect Phase Diagrams from Ab Initio Calculations and CALPHAD Concepts: Jing Yang1; Mira Todorova1; Tilmann Hickel1; Joerg Neugebauer1; 1MPI fuer Eisenforschung
Recent progress in experimental atomic-scale characterization techniques allows to study the local chemical composition at individual defects such as interfaces, grain boundaries, dislocations or surfaces. These experiments show a surprisingly rich set of structural and chemical phenomena, going well beyond simple Gibbs isotherms. To understand and eventually utilize the large number of possible defect structures, phases and phase transitions the construction and utilization of defect phase diagrams becomes mandatory. In the presentation we will show how a combination of techniques originally developed for ab initio surface phase diagrams can be combined with CALPHAD concepts to construct such diagrams. The opportunities and the insights that can be gained will be discussed for several defect types and materials systems.
9:00 AM
First Principles Calculation of Phase Diagrams Including Configurational and Vibrational Entropic Contributions: Wei Shao1; Sha Liu2; Javier Llorca3; 1Technical University of Madrid & IMDEA Materials Institute; 2Yanshan University; 3IMDEA Materials Institute & Technical University of Madrid
The phase diagram of different alloys of technological interest is predicted from first principles calculations and statistical mechanics including the effect of configurational and vibrational entropy. The formation enthalpy of different configurations was accurately predicted as a function of temperature by means of cluster expansions that were fitted from first principles calculations. The vibrational entropic contribution of each configuration was determined from the bond length vs. bond stiffness relationships for each type of bond and the Gibbs free energy of the different phases was obtained as a function of temperature from Monte Carlo simulations. The strategy was applied to determine the phase diagram of Al-Cu, Al-Li, Al-Cu-Li alloys and the computed phase diagrams were compared with the current experimental phase diagrams in the literature. They provided new insights and information that is sometimes missing in the experimental phase diagrams due to the limitations imposed by the kinetics of phase changes.
9:20 AM
DFT Study of the NiTi-X Systems for Shape Memory Alloys (SMAs) Design: Guillermo Vazquez Tovar1; Sina Hossein Zadeh1; Sayan Samanta1; Axel Van de Walle1; Raymundo Arróyave1; 1Texas A&M University
Ni-Ti based formulations of Shape Memory Alloys (SMAs) are of interest for actuator and energy harvesting applications albeit with shortcomings. Introduction of foreign elements to the alloy’s matrix has been proposed to lower operating temperatures and lower thermal hysteresis which may greatly benefit energy efficiency. Therefore, to assess and contribute to the understanding of higher order SMAs and the challenges they provide, a first-principles thermodynamic assessment of NiTi-X systems (where X = Hf,Cu) has been carried out. Here we construct a CALPHAD model from fitting to few electronic structure calculations on structures as per the SQS formalism over a composition grid. Results from the model and experimental observations are compared for the transformation temperature and hysteresis to unveil cheaper alloy design pathways for optimal thermal properties.
9:40 AM
Hydrogen Accommodation, Hydride Decomposition, and Hydride Phase Stability in the TiZrNbHfTa High Entropy Alloy: Christopher Moore1; Jack Wilson1; Jack Astbury2; Caitlin Taylor3; Michael Rushton1; Simon Middleburgh1; 1Bangor University; 2Tokamak Energy; 3Los Alamos National Laboratory
Effective hydrogen storage systems have been of significant interest to the green energy sector in terms of transportation, long-term storage, and energy production for many years. Poor H/M ratios, unfavourable desorption characteristics and degradation of the hydrogen storage materials during cycling are some of the issues that have hindered development of effective compounds. The high entropy alloy TiZrNbHfTa can satiate many of these critical criteria due to its ability to form a stable dihydride and to fully desorb stored hydrogen without degradation of the material. Hydrogen accommodation in the TiZrNbHfTa high entropy alloy has been explored across a range of H/M ratios and the hydride decomposition temperature range has been predicted using density functional theory. A sieverts style apparatus has been constructed to perform hydrogenation reactions on the alloy, this will allow an investigation into the presence of hydrogen promoting the formation of vacancies, in accordance with previous computational models.
10:00 AM Break
10:20 AM Invited
Modeling of Spontaneous PE to OE Transition in Carbide Precipitation: Qing Chen1; Kaisheng Wu2; Johan Jeppsson1; John Ågren3; Paul Mason4; 1Thermo-Calc Software AB; 2Thermo-Calc Software Inc; 3KTH; 4Thermo-Calc Software Inc.
The mixing of fast and slow diffusers leads to fascinating ortho-equilibrium (OE), para-equilibrium (PE), and non-partitioning local equilibrium (NPLE) solid phase transformations in steels. The natural transition between these phase transformations is even more intriguing and its theoretical treatment and modeling are challenging. In this work, we developed a simple model capable of dealing with the spontaneous PE to OE transition in simulating carbide precipitation in steels. The model has been implemented in TC-PRISMA, a computational tool to treat concurrent nucleation, growth, and coarsening of multiple-phase precipitates in multicomponent alloy systems. TC-PRISMA is available as a module in the Thermo-Calc Software package and has direct access to thermodynamic and kinetic databases developed for various kinds of alloys over decades. The proposed model has been applied to simulate the precipitation of cementite during the tempering of steels. A few case studies will be shown and discussed.
10:50 AM
A Novel Approach to Realizing Linear-Superleastic Behavior in NiTi SMA Using Precipitate Dissolution: Hariharan Sriram1; Longsheng Feng2; Yunzhi Wang1; 1Ohio State University; 2Lawrence Livermore National Laboratory
NiTi shape memory alloys (SMA) have various applications as cardio-vascular stents, actuators, and sensors. The shape memory effect is due to the reversible austenite to martensite transformation and the associated strain release. However, the large hysteresis (non-linear pseudoelasticity) observed in SMAs significantly impacts the efficiency and precision control. We propose a novel approach to tame martensitic transformation in NiTi by engineering concentration modulation (CM) in the parent austenite phase through the dissolution of Ni4Ti3 nanoprecipitates (observed in Ni-rich NiTi SMAs) to form a complex interpenetrating architecture with continuous variations in martensitic start temperatures. We show through Phase field simulations that the induced CMs in the parent phase effectively control the strain release by acting as nano-confinements to the martensitic transformation. A parametric study of the effect of the CMs wavelength and amplitude on the stress-strain behavior in NiTi SMAs will be presented.
11:10 AM
First-principles Tools for the Design of High Temperature Materials: Anirudh Raju Natarajan1; 1EPFL
Materials used in high temperature applications are carefully engineered to achieve optimal mechanical properties and chemical durability. Refractory alloys comprising elements from groups four, five and six of the periodic table are an emerging class of high-temperature materials that promise high strength and high thermal stability. However, relationships between alloy chemistry, processing strategies and material properties remain unclear. In this talk, I will highlight how first-principles calculations coupled with statistical mechanics techniques can be used to rigorously describe the thermodynamic and kinetic properties of multicomponent alloys. High-throughput calculations will be used to discern design rules for the formation of single phase multi-principal element refractory alloys. Diffusion mechanisms and phase transformations in multicomponent refractory alloys will also be highlighted. The techniques and results presented in this talk provide important insights for the design of refractory alloys.
11:30 AM
Progress in Design of High-performance Alloys Guided by Phase-field Simulations: Yuhong Zhao1; 1North University of China
Phase field aided design plays a more and more important role in material design, material processing control and optimization. Integrating continuous phase field model, first principle calculation and dislocation dynamics calculation aided experimental design, a new type of spinodal decomposition strengthened ultra-high specific strength magnesium alloy and high strength/high toughness copper alloy were prepared. Based on the unity of the classical thermodynamic free energy model, integrate the multi-level phase field simulation of microstructure (continuous phase field, crystal phase field and micro diffusion phase field), the simulation of macro process multi field (flow field, temperature field and defect prediction) and the casting body data and process knowledge information, and design and optimize the liquid forming process of alloy structural parts and typical cases across scales are presented; Finally, the thinking and Prospect of integrated computing materials technology for engineering applications are introduced.