Metal Powder Synthesis and Processing: Session I
Sponsored by: TMS Powder Materials Committee
Program Organizers: James Paramore, Texas A&M University; Iver Anderson, Iowa State University Ames Laboratory; Kyle Tsaknopoulos, Worcester Polytechnic Institute

Monday 8:00 AM
October 10, 2022
Room: 323
Location: David L. Lawrence Convention Center

Session Chair: Kyle Tsaknopoulos, Worcester Polytechnic Institute; James Paramore, United States Army Research Laboratory; Iver Anderson, Iowa State University Ames Laboratory


8:00 AM  
Synthesis and Characterization of Gas Atomized Ultra-high Strength Steel Powder Feedstock for Additive Manufacturing: Thinh Huynh1; Kevin Graydon1; Brandon McWilliams2; Kyu Cho2; Yongho Sohn1; 1University of Central Florida; 2DEVCOM US Army Research Laboratory
    A novel ultra-high strength steel alloy was gas atomized to produce powder feedstock for additive manufacturing. Charge alloys were inductively melted with Argon shrouding at a superheating temperature of 1800 °C, and subsequently gas atomized using Argon gas at a pressure of 2 MPa. Metal flow rate and bulk powder yield were optimized by controlling the degree of superheating, atomizing gas pressure, orifice diameter, and nozzle material type. As-atomized powders were characterized for microstructure, composition, phase constituents, particle morphology, size distribution, and flowability by using optical microscopy, electron microscopy, energy dispersive spectroscopy, X-ray diffraction, particle size analysis, and Hall flowmeter. Results are presented with due respect for phase transformations and microstructural development during rapid solidification of gas atomization.

8:20 AM  
Large Scale Manufacture and Processing of Nano-Crystalline Metal Powders by Mechanical Alloying (MA): Ryan Koseski1; Brian Gordon2; 1Veloxint CIF; 2Touchstone Research Labs
    The manufacture of nano-crystalline metal powders is an enabling route to the formation of unique bulk alloy materials. Historically, many of these powders have only been demonstrated in batch processes at the bench scale, up to roughly 1 kg. We have made engineering improvements to large scale equipment to enable the production of lots greater than 20 kg, resulting in powder volumes allowing for industrial manufacture of components and stock in commercially useful amounts. The results of the subsequent processing demonstrate the economic viability of new, MA produced alloys as well as the potential to manufacture true, bulk, microstructurally stable nano-grained metal articles.

8:40 AM  
Mechanical Alloying and Thermal Stability of Amorphous Co-C Alloys: Alex Aning1; Hesham Elmkharram1; 1Virginia Polytechnic Institute
    This work investigated the solid-state formation of Co-C amorphous alloys and their thermal stability. Amorphous Co-C alloys with compositions of 2 to 40 at% C were successfully synthesized using mechanical alloying. After 40 h of milling, complete amorphization was observed in all alloys, except for the 2 and 5 at% C alloys. Alloys with compositions through 20 at% C crystalized in two steps; the lower temperature event precipitated metastable carbide from the amorphous phase, followed by transformation to FCC cobalt and graphite from both the remaining amorphous and the metastable carbide at the higher temperature. Two types of carbides were observed - Co3C in the 2 and 5 at% C alloys, and Co2C in the higher carbon alloys through 20 at% C. For compositions above 20 at%, only one step crystallization was observed, that due to the decomposition of the amorphous phase to amorphous carbon and primarily FCC cobalt phase.

9:00 AM  
Engineering Amorphous Aluminum High Entropy Powder for Producing High Strength Cold Sprayed Deposits: Denny John1; Kazue Orikasa1; Tanaji Paul1; Cheng Zhang1; Arvind Agarwal1; 1Florida International University
    Absence of a comprehensive understanding of thermal evolution of structure and the mechanical properties in aluminum high entropy (Al HEA) powder restricts the manufacturing of high-performance deposits by cold spray. In this study, gas atomized Al HEA powder of composition Al90.05Y4.4Ni4.3Co0.9Sc0.35 (at.%) is devitrified at a systematic progression of temperatures to investigate the evolution of structural and mechanical properties for cold spray deposition. Devitrification induced nucleation and growth of crystalline aluminum and intermetallic precipitates with increasing temperature. Amorphous matrix with crystalline Al and hard Al3Sc, Al4NiY precipitates resulted in a 16% enhancement in the microhardness from 444 ± 19.37 HV in fully amorphous state to 515 ± 113 HV in devitrified state at 298 oC. Together with the understanding of the thermal evolution, devitrified powder at 298 oC will yield high strength Al alloy coating during cold spray deposition.

9:20 AM  
A Framework for Powder Evaluation with Reuse in Laser Powder Bed Fusion Additive Manufacturing: Chinmay Phutela1; Federico Bosio1; Nesma Aboulkhair1; 1Technology Innovation Institute
    Metal additive manufacturing processes such as, Laser Powder Bed Fusion (L-PBF), promise expedited production times to fabricate complex componentry with extended design freedom in both digital and material domains from powder feedstock. Existing powder production techniques are capital intensive in nature and only feasible for large-batch production. Therefore, they cannot cope with the growing interest in material design and in-situ alloying. Rapid feedstock screening methods are essential for the progression of in-situ alloying in developing the next generation L-PBF alloys. Commonly used powder blending techniques increase inhomogeneities in the powder bulk properties and hence the inter-batch processability variation. This study presents a comprehensive approach for feedstock characterisation at the particle level and bulk properties for blended powder. More importantly, the evolution of the feedstock with re-use is investigated. A systematic approach is developed to compensate for the powder heterogeneity and the structural integrity of AM-built parts produced via in-situ alloying.

9:40 AM  Cancelled
Microstructural Comparison of Metal Hydrides Fabricated Using Direct Hydriding and Powder Metallurgy Techniques: Caitlin Kohnert1; Aditya Shivprasad1; Thomas Nizolek1; Rodney McCabe1; Tyler Smith1; Michael Torrez1; Erik Luther1; Tarik Saleh1; 1Los Alamos National Laboratory
    Many metals, such as Zr, Y, and Hf, form distinct metal hydride phases upon exposure to hydrogen at elevated temperature and/or pressure. In direct hydriding (DH), machined metal samples are exposed to hydrogen at specific temperature and pressure conditions to form a metal hydride phase. LANL recently developed a powder metallurgy (PM) fabrication method for metal hydrides. Feedstock powder is first produced by direct hydriding of the metal to make a brittle metal hydride susceptible to pulverization. The feedstock powder is then processed through standard powder metallurgy procedures. Green bodies are sintered and hydrided in a single processing step. Metal to hydride phase transformations sometimes lead to interesting microstructural features, including grain size and orientation changes and twinning, which can be characterized with electron backscatter diffraction (EBSD). This talk will compare metal hydride microstructures between DH and PM techniques. LA-UR-22-22295.

10:00 AM Break

10:20 AM  
Production Research of High-cut Steels by Methods of Hot Isostatic Pressing of Powder Materials: Anton Matiukhin1; Vitalii Shyrokobokov1; Sergey Sheyko2; Anna Ben1; Elena Kulabneva1; Tetiana Matiukhina1; 1“Zaporizhzhia Polytechnic” National University; 2Zaporizhzhia National University
    The study of the patterns of powder compaction during hydro- and gas-static pressing of large briquettes of tool grades of steels is carried out. The production of high-speed steel grades by traditional steelmaking methods is complicated by the proportion of alloying elements. As a result of adding molybdenum, tungsten and vanadium to the molten metal, it settles and concentrates in the lower part of the casting. Thus, there is an uneven distribution of alloying elements in the volume of the ingot, which leads to a decrease in the quality of the finished product. The use of powder metallurgy in the production of high-speed steels makes it possible to evenly distribute alloyed elements throughout the product. The use of powder metallurgy in the production of high-speed steels makes it possible to evenly distribute alloyed elements throughout the product.

10:40 AM  
Resistance Sintering Solid-state Bonding Model: Olga Eliseeva1; Jerry Gould1; 1EWI
    Powder processing can allow for customization of alloys and precise shape control with very little waste. Currently accepted technologies like HIPing and spark plasma sintering are expensive and time-consuming. Resistance sintering of powder for consolidation is an advancement on those technologies allowing for faster processing with associated cost reduction. Previously EWI has demonstrated the ability to use resistance sintering to produce consolidated Ti billets with extremely high density. This process has been modeled previously by treating particle to particle contacts during sintering as a series of projection welds that result in consolidation. This work expands on that model to focus on the localized heating within the billets and mapping out the solid-state bonding physics of the puck during the entire weld cycle.