Hume-Rothery Symposium: Thermodynamics, Phase Equilibria and Kinetics for Materials Design and Engineering: Opening Session
Sponsored by: TMS Structural Materials Division, TMS: Alloy Phases Committee, TMS: Integrated Computational Materials Engineering Committee
Program Organizers: Carelyn Campbell, National Institute of Standards and Technology; Michael Gao, National Energy Technology Laboratory; Wei Xiong, University of Pittsburgh
Monday 8:00 AM
February 24, 2020
Room: 32A
Location: San Diego Convention Ctr
Session Chair: Carelyn Campbell, National Institute of Standards and Technology; Wei Xiong, University of Pittsburgh
8:00 AM Introductory Comments
8:10 AM Invited
William Hume-Rothery Award Lecture: Phase Diagrams, Computational Thermodynamics and CALPHAD: Ursula Kattner1; 1National Institute of Standards and Technology
Phase Diagrams are frequently hailed as roadmaps for materials and process development and are frequently graphical representations of phase equilibria as function of composition, temperature and/or pressure. The graphical representation imposes a limit on the information that can be communicated while computational thermodynamics is limited by the available computational resources. Within computational thermodynamics the CALPHAD method has established itself as a pillar for computational materials and process design and its databases are viewed as part of a materials genome. The CALPHAD method was established several decades ago for thermodynamic modeling of phase equilibria and its models have become increasingly sophisticated with time for efficient calculation of realistic phase diagrams and thermochemical properties. The conceptual design of CALPHAD models also makes them well suited for describing other phase-based properties, such as diffusion mobilities, molar volume and other thermophysical properties. Recent advances in CALPHAD modeling and database development will be discussed.
8:50 AM Invited
Tomorrow fcc Ordering Model: Nathalie Dupin1; 1Calcul Thermodynamique
Modeling the gamma gamma prime equilibria i.e. the thermodynamics of the Ni based fcc solid solution and its ordered variant based on the Ni3Al compound is of tremendous interest in the aircraft engine framework. Starting from the stoichiometric model of the gamma prime introduced in the seventies, improvements of the empirical Calphad models and their application to a large number of systems have allowed to develop commercial databases describing reasonably well phase equilibria in the industrial alloys. The recent implementation of the Effective Bond Energy Formalism opens to multi-component databases that will be faster, closer to the crystallography of the phase, more physically based and provide higher quality results.
9:30 AM Break
9:50 AM Invited
Materials Property Databases Developed by the CALPHAD Approach and Their Applications in Materials Design: Fan Zhang1; Jun Zhu1; Chuan Zhang1; Duchao Lv1; Shuanglin Chen1; Weisheng Cao1; 1CompuTherm LLC
Computer simulation has played an important role in accelerated materials design and development. Among various types of science-based models and simulation tools, the CALPHAD-type modeling tools have been widely used for understanding phase equilibria and thermodynamics of metallic alloy systems. The major achievement of the CALPHAD-type tools is that they have been successfully applied to technically important multi-component systems. The key for the successful application of the CALPHAD method is to have reliable databases for multi-component systems. Although started with thermodynamic databases, variety types of databases, such as mobility databases and thermo-physical property databases have been developed in recent years using the CALPHAD approach. These databases have generated many applications beyond thermodynamics and phase equilibria. In this presentation, we will discuss the development of various types of databases and their applications in materials design and process optimization.
10:30 AM Invited
On the Next Generation of Thermodynamic CALPHAD Databases: Malin Selleby1; 1KTH Royal Institute of Technology
With the increasing possibility to use DFT calculations and the development of computer power a new set of descriptions of the elements are being developed to replace those published in 1991. Different methods to extrapolate the solid to high temperatures and the liquid to low have been attempted. For the liquid the two-state model is used with a new extrapolation scheme for the liquid to high temperatures. Care must be taken to obey the third law also when describing the metastable states of the elements, stable and metastable end-members of solution phases, as well as compounds. With “new” elements the models for higher order systems must also be revised and improved. The partitioning order-disorder and the magnetic ordering models are also affected and therefore updated.The new models seem to be able to improve the thermodynamic descriptions. They have been applied to several unaries, binaries and a few ternary systems.
11:10 AM
The Third Generation of CALPHAD Descriptions: Case Studies on Al-C and W-C: Zhangting He1; Malin Selleby1; 1KTH Royal Institute of Technology
When developing the third generation of Calphad databases, it is critical to test the new unary descriptions in higher-order systems. In addition to testing different methods of extrapolating the solid above its melting temperature and the liquid to low temperatures, modeling compounds, stable and metastable end-members of solution phases within the framework of the compound energy formalism is then of great importance. Since the third generation of Calphad databases are valid down to 0 K, the conventional Neumann-Kopp rule should not be directly applied to describe phases or end-members as it would violate the third law of thermodynamics. Thus, new solutions are needed when developing the third generation data. The “hybrid” Neumann-Kopp/Einstein model has been used to describe the metastable end-members in the Al-C and the W-C systems. The systems were chosen since they are non-magnetic and due to the difference in melting temperatures of Al and W.