HEA 2023: Powders and Additive Manufacturing I
Program Organizers: Andrew Detor, DARPA/DSO; Amy Clarke, Los Alamos National Laboratory
Tuesday 1:40 PM
November 14, 2023
Room: William Penn Ballroom
Location: Omni William Penn
Session Chair: Ming Chen, Northwestern University
1:40 PM Introductory Comments
1:45 PM Invited
Refractory Metal Based HEAs for Medical Purposes: Karin Ratschbacher1; 1Gfe Metals and Materials GmbH
Zr-Ti-Ta-Nb based HEAs provide a great range of mechanical properties, that can be used to optimize the characteristics of medical implants to their application. An alloy development approach based on data, taken from the literature was applied. The manufacturing of fully alloyed powder is required to benefit from the advantages additive manufacturing offers to produce tailored medical implants. The manufacturing route for powder will be introduced, as well as the properties of the resulting powder. A first alloy for this application has been produced and thoroughly characterized. Samples manufactured through different powder-based methods are evaluated concerning their chemical composition, crystal structure, mechanical properties.
2:15 PM
Designing Complex Concentrated Alloys for Additive Manufacturing: Expanding the Scope of Alloy 3D Printing for Resource-constrained and Location-specific Applications: Wei Xiong1; 1University of Pittsburgh
Additive manufacturing has emerged as a highly effective approach for fabricating intricate structures with enhanced design flexibility. Expanding upon this methodology, we investigate the potential of laser-based additive manufacturing techniques, including directed energy deposition and laser powder bed fusion, for fabricating complex concentrated alloys. Specifically, we explore the feasibility of employing a powder mixture comprising the commonly used stainless steel 316L (SS316L) and Inconel 718 (IN718) to achieve exceptional print quality. This study not only addresses the demands of resource-constrained environments but also caters to the requirements of location-specific design objectives. The resulting complex concentrated alloy exhibits a refined grain structure, showcasing remarkable stability even under conditions of high-temperature homogenization. Moreover, using alloy CALPHAD-based ICME design (ICME: Integrated Computational Materials Engineering), we discovered a new composition demonstrating superior precipitation strengthening, yielding comparable strength to IN718 while reducing manufacturing costs through increased iron content.
2:35 PM
Additive Manufacturing as a Processing Pathway for Refractory BCC+B2 Alloys: Kaitlyn Mullin1; Sebastian Kube1; Carolina Frey1; Sophia Wu1; Tresa Pollock1; 1University of California Santa Barbara
Emulating the nickel-base superalloy gamma+gamma-prime microstructure in BCC+B2 refractory multi-principal element alloys (RMPEAs) is a promising alloy design strategy to achieve strength and ductility at high temperatures. Ru-based B2 precipitates have shown exceptional thermal stability and can even persist to melting, making traditional solutioning and aging pathways difficult. Though the rapid solidification velocities inherent to additive manufacturing (AM) may suppress B2 formation upon solidification, these conditions introduce extreme thermal stresses that often lead to microcracking in precipitation-strengthened superalloys. To investigate AM as a possible processing strategy for BCC+B2 RMPEAs, a selection of HfRu and TiRu based BCC+B2 compositions with different solvus temperatures are exposed to laser track experiments. The cracking behavior and solidification morphologies are characterized as a function of composition and process parameters. B2 precipitate morphologies in the melt pools are characterized after subsequent aging treatments.
2:55 PM
Leveraging Metastability in High Entropy Alloy Design for Grain Refinement in Additive Manufacturing: Akane Wakai1; Atieh Moridi1; 1Cornell University
The use of additive manufacturing (AM) techniques enables the fabrication of intricate structures with customized properties. However, the presence of coarse grains during solidification restricts the mechanical performance of AM-produced components. This study aims to exploit the metastable phase transformations within high entropy alloys (HEAs) to enhance grain refinement during AM without the need for post processing. Specifically, by varying the Mn content in a FeMnCoCr HEA, we can systematically evaluate the effect of solidification pathway on microstructure and properties. This comprehensive exploration combines thermodynamic modeling, operando synchrotron X-ray diffraction, multiscale microstructural analysis, and mechanical testing to develop advanced HEAs for AM. These findings provide insight into the solidification fundamentals of HEAs and help establish an alloy design guideline to enhance mechanical properties in AM and contribute to pushing the boundaries of AM technology.
3:15 PM Break
3:35 PM
Development and Characterisation of a New TiVNbMo-based Refractory High Entropy Alloy.: Lucy Farquhar1; Jonah Shrive1; Robert Snell1; Iain Todd1; Russell Goodall1; 1University Of Sheffield
Refractory high entropy alloys (RHEAs) offer an interesting opportunity to tailor specific material properties and especially to retain high strength at elevated temperatures. Additive manufacturing (AM) has also been successfully utilised to make these difficult to process RHEAs with increased strength and refined microstructures, though few alloys have yet been specifically developed with this process in mind. Therefore, in this work the development of a new AM-processable TiVNbMo-based RHEA is presented from theoretical design and modelling stages, experimental weld tracks, to the resulting alloy manufactured by laser powder bed fusion (LBPF). These LPBF builds were completed using both bespoke pre-alloyed powder and off-the-shelf elemental powder, with a comparison between the two feed stocks and the resulting microstructures of the parts built. The thermal and mechanical properties and oxidation behaviour of the alloy are then characterised and compared with the properties of some conventional alloys.
3:55 PM
High-throughput Computation and Process Design for Metal Additive Manufacturing: Exploring the Fe-Co-Cr-Mn-Ni System as a Case Study: Sofia Sheikh1; Brent Vela1; Pejman Honarmandi1; Peter Morcos1; David Shoukr1; Abdelrahman Kotb1; Raymundo Arroyave1; Ibrahim Karaman1; Alaa Elwany1; 1Texas A&M University
High entropy alloys (HEAs) have gained interest for their exceptional properties, while additive manufacturing (AM) enables the fabrication of intricate HEA structures. However, AM exploration of HEAs is limited. Determining optimal processing conditions is crucial to produce defect-free parts. Surveying the printability of alloys in terms of composition and processing is challenging through experiments alone. Thus, high-throughput (HTP) computational frameworks are essential for guiding the search for printable alloys and processing parameters. In this work, various criteria for process-induced defects are considered, properties are predicted using CALPHAD, processing parameters are determined, and melt pool profile are obtained by thermal models. We verify the framework by constructing printability maps for the CoCrFeMnNi system. Furthermore, the framework searches for alloys in the Co-Cr-Fe-Mn-Ni HEA constrained-space to reduce the formation of macroscopic defects. This framework enables systematic investigation of HEA printability and serves as a valuable tool for AM-centered alloy design in HEAs.
4:15 PM
Cold Spray Additive Manufacturing of Refractory High Entropy Alloys using Elemental Powder Blends: Matthew Dunstan1; Isaac Nault1; Frank Kellogg2; 1US Army Research Laboratory; 2Survice Engineering
In cold spray additive manufacturing (CSAM) three dimensional components are produced by spraying powder materials onto a substrate at supersonic speeds which causes the material to deform and create bonds on impact. CSAM has many benefits including high deposition rates, large build volumes, and solid-state processing. Due to many refractory high entropy alloys (RHEA) having high strength and low ductility producing these alloys in complex geometries can be challenging. In order to enable complex geometries of these alloys this work investigates the use of elemental blends of RHEAs with CSAM to produce green compacts which are subsequently sintered in order to homogenize and densify the alloy. By using elemental blends, CSAM can take advantage of the higher sprayability of the base elements (e.g., Al, Cr, Nb, Ti) in order to spray non-sprayable elements (e.g., Mo, W) and ultimately produce a refractory high entropy alloy.
4:35 PM
Enhanced Reduction of Stable Oxides: A Synergistic Effect for Processing of a High Entropy Alloy: Wookyung Jin1; Prince Sharma1; Animesh Kundu1; Ganesh Balasubramanian1; Helen Chan1; 1Lehigh Unversity
High entropy alloys can be successfully fabricated by the reduction of the constituent oxide powders. During the processing of Cantor alloy CoCrFeNiMn using this technique, it was found that even highly stable oxides such as Cr2O3 and MnO could be partially reduced by annealing in 3% H2 -Argon, at temperatures 1000 – 1250 oC. In addition to the entropy contribution (ΔSss), it is proposed that reduction is enhanced due to the negative enthalpy of solid solution (ΔHss) of the metal in the HEA composition. A series of binary, ternary and quaternary alloys (derived from the elemental set - Co, Cr, Fe, Ni, Mn) were processed by oxide reduction. In each case, the composition of the metallic phase, as well as the microstructure and overall extent of reduction were determined. These results will be discussed in the context of predictions based on values of ΔHss and ΔSss calculated from first principles.
4:55 PM
Rapid Solidification Behavior of Refractory Multi-principal Element Alloys: Megan Le Corre1; Kaitlyn Mullin2; Ruben Ochoa1; Adriana Eres Castellanos1; Tresa Pollock2; Amy Clarke1; 1Colorado School Of Mines; 2University of California, Santa Barbara
Additive manufacturing (AM) of high temperature refractory alloys and new refractory multi-principal element alloys (RMPEAs) promises to circumvent potential fabrication challenges associated with traditional manufacturing processes like thermomechanical processing. While recent studies of RMPEAs by AM have revealed promising results, much work remains to evaluate the foundational solidification behavior associated with and responsible for the resulting microstructures and properties. Thermal gradients and solidification velocities produced by laser processing parameters in single track melts of refractory alloys were determined using heat transfer modeling and computational fluid dynamics software. These characteristics are then correlated to predicted microstructural morphologies using the Ivantsov Marginal Stability model, the Hunt modification to the Gaümann columnar to equiaxed transition model, and the Scheil-Gulliver model. Agreement or discrepancy between microstructural predictions and experimentally observed microstructures can be used to calibrate solidification models, thereby enabling tailored microstructures and properties in these alloys.