Alloy Phase Transformations at Elevated Temperatures: Session II
Sponsored by: TMS High Temperature Alloys Committee, TMS Phase Transformations Committee
Program Organizers: Dinc Erdeniz, University of Cincinnati; Benjamin Adam, Oregon State University; Jonah Klemm-Toole, Colorado School of Mines; Eric Lass, University of Tennessee-Knoxville; Ashley Paz y Puente, University of Cincinnati; Sophie Primig, University of New South Wales; Chantal Sudbrack, National Energy Technology Laboratory
Tuesday 8:00 AM
October 11, 2022
Room: 326
Location: David L. Lawrence Convention Center
Session Chair: Sophie Primig, University of New South Wales
8:00 AM Invited
Impact of Manufacturing Processes on Phase Transformations in High-temperature Alloys: Some Thoughts Based on Representative Case Studies: Wei Xiong1; 1University of Pittsburgh
High-temperature alloys are critical for engineering applications and thus have received much attention during advanced manufacturing innovation. The fundamental knowledge of phase transformations in alloys usually requires a good understanding of multicomponent thermodynamics and diffusion kinetics. A successful materials design requires a comprehensive evaluation of the process-structure-property relationships, for which the processing influence on phase transformation becomes rather significant. However, when applying theoretical knowledge to predict and identify the microstructure-property relationships, uncertainty quantification and propagation due to different processing steps become vital but often tend to get forgotten. In this talk, several examples of phase transformations in superalloy will be introduced. Some insights into the processing impact on microstructure evolution will be presented through the comparison of phase transformations between different manufacturing processes. The discussion highlights the requirement of applying correct phase transformation guidelines, such as continuous cooling transformation and isothermal transformation diagrams, to optimize processing in different manufacturing techniques.
8:30 AM Invited
Examining the Influence of Nitride Precipitation on the Performance of Additively Manufactured Nickel Superalloys: Mark Stoudt1; James Zuback1; Andrew Iams1; 1National Institute of Standards and Technology
The combination of strength, corrosion resistance, and weldability makes IN625 attractive for additive manufacturing applications. A nitrogen content of approximately 0.1 percent promoted precipitation of unanticipated nitrides in both the as-deposited and post-process hot isostatically pressed (HIP) conditions. Cubic nitrides (MN), tetragonal Z-phase (CrNbN), and diamond-cubic η-nitrides (M6N) were found within the matrix containing relatively low Fe, Ti, and high Si contents, while a composition with higher Ti and Fe contents resulted in only MN nitrides. After HIP, many nitrides persisted in both materials with slight changes in secondary phase composition and lattice parameters. These stable nitrides present a potential pathway to enhanced high temperature and creep properties, but their impact on corrosion performance is currently unknown. A series of measurements evaluated the electrochemical performance of both alloys under free corrosion and potentiostatic conditions. The experimental protocol, and results from the electrochemical and microstructural analyses will be presented and discussed.
9:00 AM
Solidification Modelling With CALPHAD: Process Applications of Equilibrium and Non-equilibrium Models and When to Use Them: Adam Hope1; Ben Sutton1; 1Thermo-Calc Software Inc
Solidification is an essential part of many manufacturing processes, and rarely proceeds under conditions of thermodynamic equilibrium. Mass and heat transport near the solid-liquid interface control solute segregation as the microstructure evolves. This impacts the solidification temperature range, formation of secondary phases, and residual solute segregation in the solid. Many models exist to predict both equilibrium and non-equilibrium solidification behaviour using CALPHAD-based tools. Model selection depends on the alloy chemistry and process parameters surrounding a given solidification process. For example, the rapid solidification of laser based fusion processes can necessitate the use of solute trapping models, which have recently been coupled with CALPHAD. Conversely, the slower cooling of casting warrants consideration of back-diffusion in the solid. This presentation will outline the various CALPHAD-based solidification models, and discuss when each should be applied using industry focused case studies.
9:20 AM
In-situ Neutron Characterization of Thermomagnetic Processes Utilizing Direct Induction Heating: Zachary Tener1; Dante Quirinale1; Cory Fletcher1; Elijah Stevens1; Bart Murphy1; Gerry Ludtka2; Michael Kesler1; 1Oak Ridge National Laboratory; 2University of Florida
Thermomagnetic processing, or the application of a magnetic field during heat treatment of materials, has a variety of beneficial effects on many conventional and experimental processes. These benefits can include lower annealing temperatures, faster kinetics, a transformed phase space, and an improved energy cost of the desired processes. However, little work exists to explain the underlying causes of these observable effects. We have designed and tested a new in-situ, induction heating insert for the direct heating of materials, designed in tandem with superconducting magnet sample environments on neutron characterization beamlines. We will be discussing the development of this design, the controls that are necessary for its use, and the finer points of operating this new capability in neutron scattering experiments. This material is based upon work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Advanced Manufacturing Office award number DE-EE0009131.
9:40 AM Invited
Metallic Alloy Microstructure Prediction and Control with Processing: Amy Clarke1; 1Colorado School of Mines
To make high-performance metallic alloys for extreme environments, the prediction and control of microstructure development with processing is needed. For example, solidification is the first step experienced by metallic alloys at elevated temperatures. The solid-liquid interface velocities and thermal gradients experienced will have a profound impact on microstructure selection, which impacts properties and will set the stage for subsequent microstructure development in the solid state. Improved understanding of phase transformations and microstructure development in conventional and model metallic alloys with processing, aided by in-situ/ex-situ characterization, is needed. In-situ imaging of solidification dynamics in Ni, Ti, and/or Al alloys, including during simulated additive manufacturing, and microstructure development in novel Ti and/or multi-principal element alloys during thermal cycling and/or thermomechanical processing in the solid state are highlighted. This new knowledge is needed to predict and control microstructure development and to design alloys and processes for performance in extreme environments.
10:10 AM Break
10:30 AM Invited
Tracking Changes in Microstructure and Mechanical Properties of Electron Powder Bed Fusion Produced Inconel-738: Andrew Breen1; Bryan Lim1; Felix Theska2; Alec Day1; Sophie Primig2; Simon Ringer1; 1University of Sydney; 2University of New South Wales
Electron powder bed fusion technology offers exciting opportunities for producing Ni-based superalloy components from alloys such as Inconel-738 (IN738) but questions remain as to how the processing parameters influence the resulting microstructure and properties. One important consideration is how gamma prime, the major strengthening phase, evolves throughout a build and how this can be controlled for optimal mechanical performance. In this presentation, the changing morphology and chemistry of gamma prime in a cuboid IN738 build printed using a random scan strategy on an Arcam Q10 system is reported on. Atom probe tomography (APT) and complementary scanning electron microscopy (SEM) and electron back-scattered diffraction (EBSD) are used to quantify changes in volume fraction, chemistry and ordering behaviour in gamma prime throughout the build height. Indentation hardness tests are also performed to determine how the changing nature of gamma prime influences mechanical properties.
11:00 AM
Phase Stability in Cast and Additively Manufactured Al-9 wt%Cu-6 wt%Ce Alloy: Alice Perrin1; Sumit Bahl1; Donovan Leonard1; Alex Plotkowski1; Amit Shyam1; Ryan DeHoff1; Ying Yang1; 1Oak Ridge National Laboratory
Additive manufactured (AM) eutectic Al alloy systems have been studied extensively for advantageous thermal and mechanical properties due to the interesting and refined microstructures and Al-Cu-Ce alloys has been identified as a promising system of study. Phase identification of the microstructure of AM Al-Cu-Ce has revealed the Al8Cu3Ce phase, a phase which was not previously included on simulated or experimental phase diagrams of the cast Al-Cu-Ce system, prompting additional thermodynamic modelling of the system. These models were experimentally validated with cast Al-Cu-Ce alloys. We found that despite the refined microstructure of the AM alloys, the phases formed were consistent with the cast samples, suggesting that AM processing does not significantly affect the formation and stability of phases compared with traditional casting. These results have resolves inconsistent previous descriptions of the Al-Cu-Ce ternary phase diagram in the Al-rich region.