Refractory Metals 2023: Alloy Design - Ultimate Plus
Sponsored by: TMS Structural Materials Division, TMS: Refractory Metals & Materials Committee
Program Organizers: Brady Butler, US Army Research Laboratory; Todd Leonhardt, Rhenium Alloys Inc.; Matthew Osborne, Global Advanced Metals; Zachary Levin, Los Alamos National Laboratory
Wednesday 8:30 AM
March 22, 2023
Room: Aqua E
Location: Hilton
Session Chair: Zak Fang, University of Utah
8:30 AM Invited
BIRDSHOT: An Accelerated Program for the Discovery and Optimization of Refractory High Entropy Alloys: Raymundo Arroyave1; Brent Vela1; Danial Khatamsaz1; William Trehern1; Ibrahim Karaman1; Weiwei Zhang2; Douglas Allaire1; Paul Mason2; Duane Johnson3; Prashant Singh3; Axel van de Walle4; Miladin Radovic1; Ankit Srivastava1; 1Texas A&M University; 2ThermoCalc; 3Ames Lab; 4Brown University
The Refractory High Entropy Alloy (RHEA) space is vast and it is impossible to explore using conventional approaches to materials discovery. In this talk, we present the Batch-wise Improvement in Reduced Design Space using a Holistic Optimization Technique (BIRDSHOT) framework. BIRDSHOT incorporates the strengths of ICME and combinatorial methods, while addressing all their drawbacks, as it: (i) employs novel machine learning (ML) and data-driven search algorithms to identify efficiently the feasible regions amenable to optimization; (ii) exploits correlations to fuse simulations and experiments to obtain efficient ML models for predicting PSPP relations; (iii) uses Bayesian Optimization (BO) to make globally optimal iterative decisions regarding which region in the RHEA space to explore/exploit, leveraging existing models and data; (iv) is capable of carrying out multiple optimal parallel queries to the design space. We show how we have been using BIRDSHOT to search for next generation refractory alloys for turbine engine applications.
9:00 AM
Concurrent Design of a Multimaterial Niobium Alloy System for Next-generation Turbine Applications: Pin Lu1; James Male1; Zhi Liang1; Peter Jacobson1; Jiadong Gong1; Greg Olson1; 1QuesTek Innovations
QuesTek Innovations and team are designing and developing a comprehensive solution for a next-generation turbine blade alloy and coating system capable of sustained operation at 1300°C. Concurrent design of material and component is proposed to accelerate adoption of the designed materials into next-generation engines. QuesTek is applying its ICME-based models and extensive materials design experience to design a niobium (Nb)-based multi-material alloy system consisting of a ductile, precipitation-strengthened, creep-resistant alloy for the turbine “core” combined with an oxidation-resistant, bond coat-compatible Nb alloy for the “case.” Leveraging additive manufacturing techniques such as directed energy deposition enables fabrication of a turbine blade structure with composition and microstructure tailored to provide location-specific properties, resolving the inherent conflict between mechanical performance and oxidation resistance. The multi-material Nb alloy will achieve a combination of properties suitable for a variety of gas or industrial turbine components such as blade, vane, and panel structures.
9:20 AM
Data-augmented Property Modeling for Accelerated Closed-loop Multi-Objective Design of Refractory High Entropy Alloys for ULTIMATE: Brent Vela1; Danial Khatamsaz1; William Trehern1; Cafer Acemi1; Prashant Singh2; Douglas Alliare1; Raymundo Arroyave1; Ibrahim Karaman1; Duane Johnson2; 1Texas A&M University; 2Ames Laboratory
Refractory multi-principal element alloys (MPEAs) are thought to be likely candidate materials to enable next-generation gas turbine engines. These refractory MPEAs must be ductile at room temperature such they are formable and simultaneously retain their yield strength (> 200 MPa) at 1300C. However, the ‘strength-ductility trade-off’ makes the design of such an alloy difficult. Bayesian optimization frameworks enable the efficient exploration of such high-dimensional design spaces and identification of Pareto-optimal alloys. Importantly, Bayesian optimization can incorporate prior knowledge into the search scheme. Despite this, often high-fidelity prior knowledge of these systems is sparse, yet reduced order models (ROMs) exist that can inject the optimization scheme with useful information concerning objectives. In this work we use ROMs as informative priors, update the priors with high-fidelity data, creating machine learning augmented ROMs, and use said augmented ROMs within a multiple objective batch Bayesian optimization scheme to design high strength ductile MPEAs.
9:40 AM
High-throughput Design, Synthesis, and Characterization of Refractory Multi-principal Element Alloys (MPEAs) for ULTIMATE: Eli Norris1; Cafer Melik Ensar Acemi1; William Trehern1; Brent Vela1; Raymundo Arroyave1; Ibrahim Karaman1; 1Texas A&M University
Refractory alloys are promising for high-temperature applications because of their high strength at elevated temperatures, high thermal conductivity, low thermal expansion coefficient, and operability under oxidizing conditions. Eighty-eight refractory multi-principal element alloys (MPEAs) have been designed to exhibit a single BCC phase at elevated temperatures, target yield strength (>200 MPa) at 1300 ℃, and a narrow solidification range for additive manufacturability. The designed compositions are synthesized with high-throughput vacuum arc melting and characterized with electron microscopy (SEM/EDX), XRD, Vickers microhardness, and nanoindentation experiments. In the as-cast state, all samples had BCC phase with dendrites. Based on diffusion calculations centered around the compositional difference and dendrite arm spacing, homogenization heat treatments at 1800°C and 1925°C are performed. Compression experiments are then performed at high temperatures to compare with predicted high-temperature properties. Collected experimental data is fed back into the computational and experimental discovery loop to further improve models.
10:00 AM Break
10:15 AM
High-throughput Design, Synthesis, and Characterization of W-based Refractory Multi-principal Element Alloys (MPEAs): Cafer Melik Ensar Acemi1; William Trehern1; Eli Norris1; Brent Vela1; Peter Morcos1; Raymundo Arroyave1; Alaa Elwany1; Ibrahim Karaman1; 1Texas A&M University
Refractory alloys, including tungsten alloys, are promising for high-temperature applications due to their high strength at elevated temperatures, high thermal conductivity, low thermal expansion coefficient, and resistance to creep. Forty-three refractory multi-principal element alloys with tungsten contents of more than 30 at.% are designed to have single BCC phase at high temperatures, target yield strength (>50 MPa) at 2000°C, and narrow solidification range for 3D printability. The designed compositions are synthesized via high throughput vacuum arc melting. The samples are then characterized using electron microscopy (SEM/EDX), XRD, Vickers microhardness, and nanoindentation experiments. In as-cast state, majority of samples had BCC phase with dendrites. Homogenization heat treatments are performed at 2000°C to eliminate dendritic structure after diffusion calculations based on the compositional differences measured in the dendrites. Compression experiments are conducted at high temperatures to compare the initial model predictions and the experimental strength results, which will be presented in detail.
10:35 AM
Design and Correlative Mapping Characterizations of High-entropy Alloys for Nuclear Applications: Pedro Ferreirós1; Kan Ma1; Andrew London2; Alexandra Cackett3; Kiumars Aryana4; Patrick Hopkins4; Alexander Knowles1; 1University of Birmingham; 2CCFE, UK Atomic Energy Authority; 3National Nuclear Laboratory Limited; 4University of Virginia
High-entropy alloys (HEAs) are promising candidates for generation-IV fission and fusion energy, offering high melting points, high strength and irradiation tolerance. However, its selection and design remain a major challenge within the vast size of composition and predictive capability. In this work, we explore several million combinations using the Alloy Search and Predict (ASAP) software, which screens for single-phase stability at high temperature. Further, we select HEAs with low neutron absorption cross-section. These HEAs have refractory metals (RM) as their main constituents providing great potential for application in extreme environments. A group of RM-HEAs is here produced and studied by diverse correlative mapping characterization techniques. This methodology allowed access in the same area to individual phase properties such as chemical composition, crystal structure, grain orientation, thermal conductivity, hardness and elastic modulus. These complimentary mappings are optimal for a quick and thorough characterization and especially useful for optimizing the alloy design.
10:55 AM
ULTIMATE: Alloy Designs for High Temperature Mo-Si-B Base Systems: John Perepezko1; Dan Thoma1; Longfei Liu1; Phalgun Nelaturu1; Ankur Agrawal1; Zahabul Islam2; Fan Zhang3; Laurence Marks4; 1University of Wisconsin-Madison; 2Bowling Green State University; 3Computherm LLC; 4Northwestern University
Among the refractory metal alloys (RMA) Mo-Si-B alloys have received much attention due to their high melting point and high temperature strength, but they also have some remaining challenges to improve ductility, lower density and enhance environmental resistance. In order address this issue, a new series of Mo-Si-B alloys in the Moss+T2 +Mo2B three phase region has been designed. Selected additions of Al and Ti enable a density reduction to below 9 gm/cm3. The processing of RMAs to manufacture dimensionally controlled shapes in a commercially cost-effective way is challenging. To circumvent this challenge, an additive manufacturing (AM) route offers a new, rapid and effective strategy. With AM methods alloying is accomplished by the melting and reactive synthesis of component powder mixtures to full density. This approach has been demonstrated to yield the fabrication of homogeneous alloys with well-defined shapes, full density and with the desired microstructures and structural performance.
11:15 AM
Understanding Process-performance Trade-offs in Additively Manufactured Refractory Metals and Refractory HEAs to Drive Future RHEA Design: David Crudden1; Shaumik Lenka1; Yining He1; Atsushi Sato1; Pimin Zhang1; Georgina Frater1; Yousefiani Ali2; Austin Mann2; 1Alloyed Inc; 2Boeing
Additively manufactured AM refractory metals have significant potential for ultra-high temperature applications in turbomachinery and propulsion. Currently, the use of AM refractory alloys has been restricted as the processability and high temperature mechanical performance is not well understood. In this paper the processing window for gas atomized powders of niobium alloys C-103 and FS-85 as-well-as a refractory high entropy alloy ( V20Nb20Mo20Ta20W20) are compared using laser powder bed fusion. The high temperature tensile and creep properties of the alloys is measured using a novel electrothermal mechanical testing machine (ETMT). It is demonstrated that ETMT is reliable method to measure the high temperature properties of refractory materials. The analysis presented captures the process performance trade-offs between conventional niobium alloys and the V20Nb20Mo20Ta20W20 RHEA. The authors will describe developments in innovative computational and experimental alloy design techniques which are being used to discover new and improved RHEA compositions in an accelerated manner.