Hume-Rothery Symposium: Accelerated Measurements and Predictions of Thermodynamics and Kinetics for Materials Design and Discovery: Session VI
Sponsored by: TMS Structural Materials Division, TMS: Alloy Phases Committee
Program Organizers: Wei Xiong, University of Pittsburgh; Shuanglin Chen, CompuTherm LLC; Wei Chen, University At Buffalo; James Saal, Citrine Informatics; Greta Lindwall, KTH Royal Institute of Technology
Wednesday 2:00 PM
March 17, 2021
Room: RM 35
Location: TMS2021 Virtual
Session Chair: Qiaofu Zhang, QuesTek Innovations LLC
2:00 PM Invited
Integrated Predictive Materials Science: Filling the ICME Pipeline: John Allison1; 1University of Michigan
The transformational promise of ICME is still more dream than reality however progress is being made on many fronts. This talk will review progress within the PRISMS Center to create and make available a framework for accelerating predictive materials science to fill the pipeline for next generation ICME capabilities. There are three key elements of this framework. This first is a suite of high performance, open-source integrated multi-scale computational tools for predicting microstructural evolution and mechanical behavior of structural metals. The second is The Materials Commons, a knowledge repository and virtual collaboration space for archiving and disseminating information. The third element of the framework is set of integrated scientific “Use Cases” in which these computational methods are tightly linked with advanced experimental methods to demonstrate the ability of the PRISMS framework for improving our predictive understanding of metals and alloys, in particular precipitate evolution and microstructural influences on mechanical behavior.
2:40 PM Invited
Phonon Anharmonicity Causes the Large Thermal Expansion of NaBr: Brent Fultz1; Yang Shen1; Claire Saunders1; Camille Bernal1; Michael Manley2; 1California Institute of Technology; 2Oak Ridge National Laboratory
Thermal expansion can be understood as a balance between phonon entropy S and elastic energy E in setting the minimum of the free energy F(V,T). For rocksalt NaBr, all the entropy is from phonons. Phonon frequencies depend on both V and T, but the conventional quasiharmonic approximation (QHA) uses V alone. We measured all phonons in a crystal of rocksalt NaBr with the ARCS inelastic neutron spectrometer. These INS measurements show an unqualified failure of the QHA to predict the temperature dependence of phonon frequencies in NaBr, even below room temperature. The QHA also fails to predict the correct thermal expansion. Anharmonic theory, using ab initio DFT calculations (VASP with s-TDEP), was much more successful. The longitudinal-optical phonon modes of NaBr have broadenings in frequency that are nearly as large as their thermal shifts. The large cubic anharmonicity originates with nearest-neighbor Na-Br bonds. [Y. Shen, et al., arXiv:1909.03150v1 (2019]
3:20 PM Invited
Multi-cell Monte Carlo Method for Phase Prediction: Maryam Ghazisaeidi1; You Rao1; Edwin Antillon2; changning Niu3; Wolfgang Windl1; 1Ohio State University; 2Naval Research Lab; 3QuesTek Innovations LLC
We propose a Multi-Cell Monte Carlo algorithm, or (MC)^2, for predicting stable phases in chemically complex crystalline systems. This algorithm takes advantage of multiple cells to represent possible phases while eliminating the size and concentration restrictions in their previous counterparts. Free atomic transfer among cells is achieved via the application of the lever rule, where an assigned molar ratio virtually controls the percentage of each cell in the overall simulation, making (MC)^2 the first successful algorithm for simulating phase coexistence in crystalline solids. During the application of this method, all energies are directly computed via density functional theory calculations. We test the method by successful prediction of the stable phases of known binary systems. We then apply the method to a quaternary high-entropy alloy. The method is particularly powerful in predicting stable phases of multicomponent systems, for which phase diagrams do not exist.
4:00 PM Invited
Insights from a Comprehensive Assessment of Diffusion Coefficients of 20 Binary Systems and a Comprehensive Diffusion Mobility Database for Magnesium Alloys: Wei Zhong1; Qiaofu Zhang2; Ji-Cheng Zhao1; 1University of Maryland; 2QuesTek Innovations LLC
A systematic assessment was performed on the diffusion coefficients and atomic mobilities of 20 binary systems that form complete solid solutions. The insights from this comprehensive assessment include: (1) reliable self-diffusion and impurity (dilute) diffusion coefficients are essential for accurate mobility assessments; (2) both intrinsic and tracer diffusion coefficients can be reliably evaluated from interdiffusion coefficients when reliable self-diffusion and impurity diffusion coefficients are available; and (3) only one parameter is necessary for each binary system to avoid over-fitting. A systematic assessment of both the measured and computed diffusion data in hcp Mg was performed using a holistic approach to yield the most comprehensive Mg mobility database to date, comprising 23 elements. This reliable mobility database will contribute to future development of advanced Mg alloys. The holistic approach developed in this study will also be very beneficial to the future establishment of reliable mobility databases for other alloy systems.