Hume-Rothery Symposium: Accelerated Measurements and Predictions of Thermodynamics and Kinetics for Materials Design and Discovery: Session V
Sponsored by: TMS Structural Materials Division, TMS: Alloy Phases Committee
Program Organizers: Wei Xiong, University of Pittsburgh; Shuanglin Chen, CompuTherm LLC; Wei Chen, Illinois Institute of Technology; James Saal, Citrine Informatics; Greta Lindwall, KTH Royal Institute of Technology

Wednesday 8:30 AM
March 17, 2021
Room: RM 35
Location: TMS2021 Virtual

Session Chair: Greta Lindwall, KTH Royal Institute of Technology; Shuanglin Chen, CompuTherm LLC

8:30 AM  Invited
Some Properties if the Multicomponent Diffusivity Matrix: John Agren1; 1Royal Institute of Technology
    The analysis of diffusion in multicomponent alloys such as high-entropy alloys requires the knowledge of the full diffusivity matrix for the phase under consideration. The values of the elements in the matrix depend on how the driving forces are expressed and what frame of reference that is used. Nevertheless, they must fulfill certain requirements giving rise to a number of issues, For example, what can be said about the sign of diffusivities and under what conditions is the matrix symmetric. The latter property is referred to as the Onsager reciprocal relations and are still sometimes controversial although they were published already 1931. One reason for the controversy may be Onsager’s somewhat complex proof. In the talk the sign of diffusivities and the validity of the Onsager relations will be discussed.

9:10 AM  Invited
A Tale of Two Approaches: From Phase Equilibria to Materials Properties : Qing Chen1; 1Thermo-Calc Software AB
     A link between the development of Dr. JC Zhao’s diffusion-multiple approach and the CALPHAD approach is revealed. They followed almost the same successful path: started with getting phase equilibrium data, then extended for obtaining diffusivity data, and recently applied to harvest more and more other materials property data. Dr. Zhao’s systematic study of a large number of alloy systems has provided indispensable input for CALPHAD modeling and contributed significantly to the development of CALPHAD thermodynamic, kinetic, and property databases. In this talk, I examine the development of the two approaches and focus on our efforts at Thermo-Calc Software in modeling various materials properties of multicomponent solution phases and providing relevant databases for materials design and process optimization.

9:50 AM  Invited
A Diffusion Mobility Database for γ/ γ' Co-Superalloys: Carelyn Campbell1; Kil-won Moon1; Maureen Williams1; Greta Lindwall2; 1National Institute of Standards and Technology; 2Royal Institute of Technology (KTH)
    Building on a previously developed Ni-based diffusion mobility database and using a newly developed Co-based thermodynamic database, a new Co-based diffusion database that includes Co-Al-W-Ni-Cr-Ta-Ti is presented. In addition to available literature data, new experimental and computational diffusion data are combined to construct this multicomponent diffusion mobility description. Diffusion couple stacks, based on the diffusion-multiple method pioneered by J-C Zhao, are used to obtain additional diffusion mobility data for 9 binary and 14 ternary systems at three different temperatures. The diffusion couple composition profiles are analyzed and then used to optimize the FCC (//947;) phase mobility parameters. Specific results for these optimizations will be presented for the Co-Al-W-Ni, Co-Al-Ni-Cr and Co-Al-Ni-Ta systems.

10:30 AM  Invited
Modeling of Diffusion and Intermetallic Phase Formation in Al-Mg Bimetallic Structures : Alan Luo1; 1Ohio State University
    Aluminum-magnesium (Al-Mg) binary system is the basis of many important Al and Mg alloys. However, it is not well understood for the thermodynamic and atomic-diffusional behaviors in Al-Mg intermetallic compounds (IMCs) which significantly influence the microstructure and performance of Al and Mg alloys. In this presentation, complete and self-consistent thermodynamic and atomic-diffusional databases have been constructed using CALculation of PHAse Diagram (CALPHAD) modeling and experimental data in literature. Based on the above assessment of the Al-Mg system, a low-temperature annealing following overcasting process has been developed to bond magnesium to aluminum alloys. The detailed microstructure evolution during annealing, including the formation and growth of Al-Mg interdiffusion layer and intermetallic phases (Mg17Al12 and Al3Mg2), was experimentally observed and predicted using CALPHAD and diffusion modeling. The precise diffusion modeling in Mg/Al interface provides an efficient way to optimize/control the interfacial microstructure of Mg/Al bimetallic structures for improved interfacial bonding.

11:10 AM  Invited
An Integrated Computational Materials Engineering (ICME) Framework for Additive Manufacturing (AM) of Ni-based Superalloys: Qiaofu Zhang1; Abhinav Saboo1; Jiadong Gong1; Greg Olson1; 1QuesTek Innovations LLC
    Additive manufacturing (AM) of Ni-based superalloys (Inconel 718, 718Plus and 625) has attracted increasing interests and attention from academia and industry. Based upon QuesTek’s Materials by DesignŽ technology, an ICME framework was developed and integrated to predict the relation chain of process-structure-property of Ni-based superalloys, and further applied to optimize the post heat treatment processes for AM-printed Ni-alloys. Following the ICME framework, an integrated software package was developed by QuesTek to effectively simulate the microstructure evolution during heat treatment, as well as the resulted mechanical properties as a function of test temperature, including both yield strength and ultimate tensile strength. This ICME framework and software package were verified with experimental results including microstructure characterization and tensile tests of AM-printed specimens. Using the ICME framework and package, QuesTek’s Accelerated Insertion of Materials (AIM) methodology was applied to quantify the property distribution of the AM-printed components.