Refractory Metals 2023: General Session - 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, Mst-16

Tuesday 2:30 PM
March 21, 2023
Room: Sapphire P
Location: Hilton

Session Chair: Brady Butler, US Army Research Laboratory / Texas A&M University


2:30 PM Introductory Comments

2:35 PM  Invited
ULTIMATE: Refractory Metal Alloys for Gas Turbine Applications – A New Age of Ultrahigh Temperature Materials: Zhigang Fang1; 1University of Utah
    High-temperature materials are the pillars of modern gas turbine technologies for aerospace and electric power generation. However, the operating temperature of gas turbines is limited by the temperature capability of the metal alloys. The state-of-the-art nickel-based superalloys can operate continuously at temperatures up to 1100 C. Recently ARPA-E of US DOE initiated a program, namely the ultra-high temperature impervious materials advancing turbine efficiency (ULTIMATE) program, to develop ultra-high temperature materials that can operate continuously at 1300 C. Such ultrahigh-temperature alloys will be based on refractory metals. The successful development of such ultrahigh temperature must meet high-temperature strength, oxidation corrosion resistance, and manufacturability requirements. This is possible today by the convergence of the tremendous power of today’s computational alloy design, the vast untapped space of refractory high entropy alloys, and the unlimited potential of additive manufacturing. This presentation will discuss the scientific rationale and the synopsis of the ARPA-E ULTIMATE program.

3:00 PM  
ULTIMATE: Machine Learning Guided Oxide Dispersion Strengthened Refractory HEA Discovery: John Sharon1; Ryan Deacon1; Soumalya Sarkar1; Kenneth Smith1; Anthony Ventura1; GV Srinivasan1; Alexandru Cadar1; Michael Gao2; 1Raytheon Technologies Research Center; 2National Energy Technology Laboratory
    To achieve higher efficiency turbine operation and reduce fuel consumption, Raytheon Technologies Research Center, collaborating with NETL, is exploring oxide-dispersion strengthened (ODS) refractory high entropy alloys (HEAs) capable of operating at temperatures above Ni-superalloy. From research conducted under the ARPA-E ULTIMATE program, this talk will describe a machine learning framework assembled to aid in identifying HEA candidates. Results from experimental screening of the predicted HEAs will be highlighted. Additive trials were performed with the top candidate using nanoparticle modified feedstock to generate the ODS microstructure. Results from the additive trials and subsequent mechanical property characterization will also be detailed. The information, data, or work presented herein was funded in part by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0001423. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

3:20 PM  
Refractory Alloys for Future Aerospace Applications: Samuel Kuhr1; Todd Butler1; Noah Philips2; John Rotella1; Donald Weaver1; David Mahaffey1; 1Air Force Research Lab; 2ATI Specialty Alloys and Components
    Refractory alloys are candidate materials for future high temperature aerospace applications, since many of these new environments exceed the temperature limits of state-of-the-art nickel superalloys. However, some of the strongest refractory alloys have been historically challenging to process through conventional wrought techniques. Reconsideration of powder metallurgy methodologies and advancements in near net shape manufacturing have expanded the processing potential and viability for implementing novel refractory alloy components. These processing enhancements lower the barrier to mechanically assessing novel refractory alloys in both cast and microstructurally relevant conditions. This concept will be discussed in relation to known high temperature strengthening mechanisms in refractory alloys. In addition, key microstructural and chemical phenomena predicted to influence mechanical performance at various length scales will be addressed.

3:40 PM  
Study of the Interactions of Niobium with Oxygen from First Principles with Bayesian Uncertainty Quantification: Colleen Reynolds1; Tresa Pollock1; Anton Van der Ven1; 1University of California, Santa Barbara
    Refractory metal BCC multi-principal element alloys are generating interest for their high strength and high temperature performance. However, the constituent materials readily interact with oxygen, both in an interstitial solid solution and through the formation of surface oxides. Niobium is an important constituent element though its interactions with oxygen are inconsistently described in the literature, warranting more detailed investigation. We have predicted the Nb-O phase diagram, ranging from the dilute solid solutions to oxygen-rich phases. Applying a novel algorithm, we systematically explored the compositional and structural space of oxygen-rich Wadsley-Roth phases. We used a first principles statistical mechanics approach that relies on cluster expansions and Monte Carlo simulations to predict elevated temperature thermodynamic properties. Bayesian uncertainty quantification techniques were implemented to assess the numerical accuracy of high temperature phase boundary predictions. We have also calculated gamma surfaces to evaluate the impact of these interstitials on the mechanical properties of niobium.

4:00 PM  
Thermal Transport Modeling in Refractory Multi-principal Element Alloys: A High-throughput Density-functional Theory Approach: Prashant Singh1; Brent Vela2; Raymundo Arroyave2; Duane D. Johnson1; 1Ames Laboratory; 2Texas A&M University
    Additive manufacturing or 3D printing of entropy-stabilized multi-principal element alloys (MPEAs) marks the key advancement in alloy synthesis. However, the complex atomic environment in MPEAs can lead to significantly different atomic mass/size (includes lattice distortion/strain) and electronic interactions (includes formation enthalpy and chemical correlations) that may reduce the thermal conductivity, opening the door for understanding the role of extreme disorder on thermal conductivity. The high-throughput density-functional theory was used to perform thermal conductivity calculations of approximately 2000 refractory based Mo-W-Nb-Ta-V-Ti-Zr-Al MPEAs. We found that element specific disorder can be used to effectively tune the thermal conductivity without compromising mechanical response such as strength and ductility. Our results present a design guide for high-performance MPEAs for additive manufacturing or 3D printing that satisfy the ULTIMATE specifications.

4:20 PM Break

4:35 PM  Invited
Bcc-Superalloy Nano-structured Tungsten and Refractory High entropy Alloys: Alexander Knowles1; 1University of Birmingham
     The microstructure template of a disordered matrix reinforced by ordered-intermetallic precipitates offers a potent design strategy for high temperature materials, enabling strength alongside damage tolerance, which has been central to the success of fcc Ni-superalloys. This has inspired a strategy of ‘bcc-superalloys’ utilising bcc-based systems that offer advantages of increased melting point and lower cost; while second-phase nano-structuring offers further advantage, for strength, creep resistance, as well giving new design bases for ductility and irradiation damage resistance.In this talk, opportunities & recent work on bcc-superalloys nano-structured tungsten and more complex alloys, including Refractory High Entropy alloys will be presented. Prospectives will be given for the onward development of these novel concept materials for application in nuclear fusion, Gen-IV fission, gas turbines and concentrated solar power.

5:05 PM  
The Phase, Microstructure and Mechanical Properties of High Entropy Mo-Nb-Ti-V-W-Zr Ultrahigh Temperature Refractory Alloy: Lavanya Raman1; Marcia Ahn1; Arindam Debnath1; Shuang Lin1; Adnan Eghtesad1; Adam Krajewski1; Shunli Shang1; Wesley Reinhart1; Allison Beese1; Bed Poudel1; Zi-Kui Liu1; Wenjie Li1; Shashank Priya1; 1Pennsylvania State University
    The discovery of more promising compositions for high temperature applications resulted in a paradigm shift in the alloy design strategy, which gave birth to refractory multicomponent high entropy alloys (HEAs). In our work, the selected Mo-Nb-Ti-V-W-Zr HEAs generated by high-throughput computational and machine learning models are manufactured utilizing vacuum arc melting and field assisted sintering technology. The experimental phase formation results are consistent with CALPHAD and Scheil simulations. The mechanical properties, such as hardness, fracture toughness, and yield strength, are evaluated. Furthermore, theoretical calculations such as surrogate model for hardness based on machine learning and crystal plasticity fast Fourier transform (CPFFT) are used to correlate the experimental mechanical data and predict the strengthening mechanism. It demonstrates an effective approach of inverse design for the new promising candidates of high-entropy refractory alloys.

5:25 PM  
ULtrahigh TEmperature Refractory Alloys (ULTERA) Database and Data Quality Assurance: Adam Krajewski1; Arindam Debnath1; Shuang Lin1; Marcia Ahn1; Hui Sun1; Allison Beese1; Wesley Reinhart1; Zi-Kui Liu1; 1The Pennsylvania State University
     ULTERA database, developed under the ARPA-E's ULTIMATE program, is aimed at collecting literature data on high entropy alloys (HEAs) to facilitate rapid discovery of new ones using forward and inverse design, with the primary focus on creep behavior, yield stress, ductility, and hardness. As of July 2022, ULTERA contains over 6,200 property-datapoints, corresponding to 2,485 unique HEAs, collected from 455 source DOIs. All data is available through a high-performance API, following FAIR principles, while statistics on it can be found at our phaseslab.com/ultera web page. The database architecture is designed to automatically integrate starting literature data in real-time with methods such as experiments, generative modeling, predictive modeling, and validations.In this presentation, we showcase the database with particular emphasis on our methods developed to assure high quality of data and screen for abnormal entries; a step crucial to creating a dataset for data-driven alloy design.

5:45 PM  
Chromium-based bcc-Superalloys Tailored by Iron Addition: Kan Ma1; Thomas Blackburn1; Pedro Ferreirós1; Christina Hofer2; Paul Bagot2; Michael Moody2; Tatu Pinomaa3; Mathias Galetz4; Alexander Knowles1; 1University of Birmingham; 2University of Oxford; 3VTT Technical Research Centre of Finland Ltd; 4DECHEMA-Forschungsinstitut
    Chromium-based alloys offer significant advantages for next-generation concentrated solar power applications at high temperatures (>600°C) related to their melting point, costs and oxidation resistance. However, the mechanical properties of Cr-based materials still need improvement to match current Ni-based superalloys, both for creep resistance and low temperature toughness. This work follows a ‘bcc-superalloy’ strengthening concept with bcc-Cr-matrix comprising ordered-bcc NiAl-intermetallic precipitates to develop Cr-based bcc-superalloys. Furthermore, Fe is alloyed to tailor the precipitate volume fraction and properties. This work addresses the demonstration of the nano-structure by electron microscopy and atom probe tomography. Results show the advantageous ageing behaviour of Cr superalloys compared to ferritic superalloys and nickel-based superalloys. The Fe-enhanced Cr-superalloys exhibit high hardness of ~500 HV0.5, dominated by solid-solution and precipitate strengthening mechanisms. Microstructure tailoring with Fe additions offers a new design pathway to improve the balance of properties in Cr-superalloys and so accelerate their development for high temperature applications.

6:05 PM  
Morphological Impacts on the Stress Relaxation and Strain Rate Sensitivity in Tungsten Heavy Alloy (WHA): Zachary Levin1; Taylor Jacobs1; K. T. Hartwig2; 1Los Alamos National Laboratory; 2Texas A&M University
    Tungsten heavy alloy composed of 90W-7Ni-2Fe rods were plastically deformed via Equal Channel Angular Extrusion (ECAE) at 300°:C, to elongate the tungsten particles. The rods were then heat treated at either 500°C, 700°C, or 1000°C, to determine the influence of the worked microstructures in the matrix and tungsten phases. The mechanical properties of heat-treated samples were compared to an as-received rod with spherical tungsten particles that was also heat-treat to 1000oC. Stress relaxation and jump test experiments were utilized to investigate the deformation mechanisms and the strain rate sensitivities relative to tungsten particle morphology. As-received, ECAE processed and postmortem WHA was also characterized by nano indentation to create young’s modulus and hardness maps, to investigate the tungsten-matrix interactions.