Additive Manufacturing of Refractory Metallic Materials: Additive Manufacturing of High Entropy Refractory Alloys
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Additive Manufacturing Committee
Program Organizers: Antonio Ramirez, Ohio State University; Jeffrey Sowards, NASA Marshall Space Flight Center; Omar Mireles, NASA; Eric Lass, University of Tennessee-Knoxville; Faramarz Zarandi, RTX Corporation; Matthew Osborne, Global Advanced Metals; Joao Oliveira, Faculdade Ciencias Tecnologias
Thursday 2:00 PM
March 23, 2023
Room: 24A
Location: SDCC
Session Chair: Joao Pedro Oliveira, Universidade NOVA de Lisboa; Antonio Ramirez, The Ohio State University
2:00 PM Invited
Novel Refractory Metals Optimized for Additive Manufacture to Improve Printability and Properties: Carly Romnes1; Fernando Reyes Tirado2; Brian Taylor2; Ryan Wilkerson2; Jeff Sowards2; Omar Mireles2; James Stubbins1; 1University of Illinois at Urbana-Champaign; 2NASA Marshall Space Flight Center
Refractory metals and alloys are of major interest for nuclear fusion systems, space nuclear power and propulsion, and hypersonic applications due to their desirable properties at elevated temperatures (>1500°C). Limitations of refractory materials include their low ductility, poor oxidation resistance, and high manufacture cost using traditional techniques. Additive manufacturing (AM) can reduce material waste associated with manufacture, but AM fabrication is impacted by the brittleness of these refractory metals. To address this concern, nanoparticles can be incorporated into AM powder to prevent cracking and improve mechanical properties. This work focuses on developing a robust approach to identify and incorporate the appropriate nanoparticles to achieve dispersion-strengthened refractory alloys with reduced cracking during AM fabrication. Changes in grain structure and microcracking were investigated before and after nanoparticle additions using optical microscopy, scanning electron microscopy, and electron backscatter diffraction. The development of the processes used to manufacture dispersion-strengthened refractory alloys will be discussed.
2:30 PM
A 3D Printable Refractory High Entropy Alloy with Excellent Mechanical Properties: Advika Chesetti1; Sucharita Banerjee1; Mohan Sai Kiran Kumar Yadav Nartu1; Sriswaroop Dasari1; Abhishek Sharma1; Rajarshi Banerjee1; 1University of North Texas
Attaining microstructural homogeneity has been a challenge in conventionally manufactured refractory alloys despite high temperature annealing treatments. The current study shows that substantially higher cooling rates in additive manufacturing (AM) processes can overcome this challenge. A low density refractory high entropy alloy (RHEA) of the composition Al10Nb15Ta5Ti30Zr40 (at.%) was successfully fabricated using the laser powder bed fusion technique from pre-alloyed powders. The conventionally cast alloy exhibited a substantially higher degree of compositional segregation as compared to the AM processed alloy. The AM processed RHEA exhibits a nanoscale co-continuous mixture of BCC and B2 phases, with an excellent room temperature compressive yield strength of ~1400MPa and ~47% plasticity as opposed to the yield strength of ~1075MPa, and ~55% plasticity, reported for the conventionally cast condition. These exceptional mechanical properties were achieved without additional annealing treatments indicating that this AM processed RHEA can be fabricated in near-net form while retaining these properties.
2:50 PM
Development and Additive Manufacturing of RHEA for Extreme Environment Applications: Ali Ozalp1; Eda Aydoğan Güngör1; 1Middle East Technical University
Refractory High Entropy Alloys are promising candidates for structural and functional applications thanks to their excellent high temperature mechanical properties, irradiation resistance, thermal stability, oxidation and corrosion resistance. In this study, Hf5Mo15Nb35Ta25Ti20 RHEA has been developed by CALPHAD-based thermodynamic modeling, and produced bydirected energy deposition (DED) method. 10x10x10 mm cuboids have been manufactured successfully followed by single track productions to optimize the DED parameter-set. It has been found that a single-phase BCC structure having porosity less than 1% is achieved. The compression test results have indicated high room temperature and elevated temperature (800 °C) strength (~1200 MPa and ~800 MPa, respectively) with considerable ductility (~25% and ~15%, respectively). Strengthening calculations indicate that main strenghtening mechanism originates from the elastic modulus mismatch of the constituent elements and agree well with the experiments.
3:10 PM
Probing Processing Defects in Novel Refractory High Entropy Alloys via In-situ Dynamic X-ray Radiography: Jerard Gordon1; 1University of Michigan
Single phase body-centered cubic (BCC) refractory high entropy alloys (RHEAs) are novel materials containing multiple principal elements in high concentrations which exhibit excellent high-temperature strength and strength retention at temperatures surpassing the melting points of conventional Ni-based superalloys. However, RHEAs generally lack appreciable room-temperature ductility resulting in critical defect formation during manufacturing and/or premature failure during mechanical loading. Additionally, RHEAs may be susceptible to solidification cracking under metal additive manufacturing (AM) processing. We present results for two novel RHEAs with potential room temperature ductility under rapid solidification environments representative of laser-powder bed fusion (L-PBF). In-situ melt pool analysis using synchrotron dynamic x-ray radiography (DXR) revealed characteristic gas and keyhole porosity within different regions of process space. Variations in keyhole depth was discovered between compositions, likely due to differences in elemental vaporization. Overall, minimal solidification cracking was observed during laser scanning, displaying the potential of these alloys for bulk high-temperature materials.
3:30 PM Break
3:50 PM
Towards High-Throughput Assessment of Printability in Refractory Alloys Systems for Laser-Powder Bed Fusion: Peter Morcos1; Brent Vela1; Cafer Acemi1; Alaa Elwany1; Ibrahim Karaman1; Raymundo Arroyave1; 1Texas A&M University
Due to the brittle nature of refractory alloys, their development has been limited by difficulties associated with their processing by conventional means. However, due to their high melting temperature and high cracking susceptibility, their Laser-powder bed fusion (L-PBF) processing is challenging. Therefore, predicting the printability of refractory alloys rank order is critical.In this work, we present a framework capable of predicting the printability of alloys in-silico. We demonstrate this framework by co-designing alloys for performance and amenability to L-PBF. Performance metrics are evaluated in a high-throughput manner within the alloy space then the alloys were filtered, yielding a tractable number of candidate alloys so they can be synthesized via arc-melting. Using CALPHAD-based property models and analytical thermal models, a suite of process-parameter informed printability criteria were calculated. These criteria were then used to rank the printability of the alloys using technique for order preference by similarity to ideal solution.