Additive Manufacturing for Energy Applications V: Characterization
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS Structural Materials Division, TMS: Additive Manufacturing Committee, TMS: Nuclear Materials Committee
Program Organizers: Isabella Van Rooyen, Pacific Northwest National Laboratory; Subhashish Meher, Pacific Northwest National Laboratory; Xiaoyuan Lou, Purdue University; Kumar Sridharan, University of Wisconsin-Madison; Michael Kirka, Oak Ridge National Laboratory; Yi Xie, Purdue University

Wednesday 8:30 AM
March 22, 2023
Room: 23A
Location: SDCC

Session Chair: Subhashish Meher, INL


8:30 AM Introductory Comments

8:35 AM  Invited
High-throughput Testing and Characterization of Materials for Nuclear Applications: Gregory Wallace1; Myles Stapelberg1; Elena Botica Artalejo1; Eleni Mowery1; Isabel Alvarez1; Alexander Siemenn1; James George Serdy1; Tonio Buonassisi1; Michael Short1; 1Massachusetts Institute of Technology
    Unlike progress in semiconductors, solar cells, or drug discovery, innovation in nuclear materials does not yet move at the speed of thought. We hypothesize that high-throughput workflow engineering centered around inference models between readily measurable properties and those of ultimate interest for nuclear structural materials (strength, ductility, toughness, thermal conductivity) can speed the pace of discovery, down-selection, development by a factor of 100. We employ a combination of thick-film physical vapor deposition or liquid-based combinatorial synthesis, followed by consolidation and microstructural optimization, and finally rapid measurements via in situ ion irradiation transient grating spectroscopy (I3TGS) and indentation plastometry during/between irradiations to correlate directly to fitness functions for each use case. We illustrate our ideas by tackling three systems: CuCr(Nb,Zr,Ti) alloys as RF antennas for plasma heating, plasma-facing first-wall high entropy alloys, and vanadium-based fusion structural materials, and will (hopefully) present our first results in this symposium.

9:10 AM  Invited
Directional Recrystallization of an Additively Manufactured Ni-base Superalloy: Zachary Cordero1; 1Massachusetts Institute of Technology
    Metal additive manufacturing processes can create intricate components that are difficult to form with conventional processing methods; however, the as-printed materials often have fine grain structures that result in poor high-temperature creep properties, especially compared to directionally solidified materials. Here, we address this limitation in an exemplary additively manufactured Ni-base superalloy by converting the fine as-printed grain structure to a coarse columnar one via directional recrystallization. The present results demonstrate how directional recrystallization of additively manufactured Ni-base superalloys can achieve large columnar grains, manipulate crystallographic texture to minimize thermal stresses expected in service, and functionally grade the grain structure to selectively enhance fatigue or creep performance in complex net-shaped components.

9:45 AM  
Microstructural Evolution of Solid State and Liquid State Advanced Manufacturing Processes for 316L Stainless Steel.: Isabella Van Rooyen1; Saumyadeep Jana1; Scott Whalen1; Luis Nunez2; Piyush Sabharwall2; Kennneth Ross1; Amrita Lall2; 1Pacific Northwest National Laboratory; 2Idaho National Laboratory
    Microstructural evolution during advanced manufacturing (AM) processes provides beneficial material development opportunities. AM techniques provide a unique opportunity to fabricate complex components which, if optimally designed, may provide options for new generation nuclear reactors to be more competitive. Specifically, AM processes with localized heat controlling abilities, can result in tailored non-equilibrium phases and fine-grained structures. Nevertheless, solid state and solid phase manufacturing processes, may have additional advantages like minimized residual stresses, homogeneous distribution of grain and phase structures. Possibilities also exist in the tailoring of phases through deformation features and therefore provide complimentary application space. Microstructure consistency and repeatability is a key feature for decision-making for identifying manufacturing processes. This presentation compares microstructural features of 316L stainless steel samples from different AM techniques, fused filament fabrication (FFF), digital light photoluminescence (DLP), powder based direct energy deposition (DED), Shear Assisted Processing and Extrusion (ShAPE™), cold spray, and friction stir additive processes.

10:05 AM Break

10:20 AM  
Characterization of LPBF and DED Additive-manufactured RAFM/Tungsten Bi-layered Specimens for Nuclear Fusion Applications: Natan Garrivier1; Malgorzata Makowska1; 1Paul Scherrer Institute
    Advances in nuclear fusion reactors core architecture have led to consider metallic additive manufacturing (AM) as the prime manufacturing process, especially for components with highly complex internal structures. Depending on the size and shape, LPBF or DED are envisioned for the production of parts. Plasma-Facing Components (PFCs) are the parts of the reactor’s vacuum vessel meant to withstand extreme conditions of neutron and particles irradiation, temperature and corrosion. Among proposed PFC materials, tungsten is the leading candidate to shield the Eurofer97 steel structural components of the reactor core. However, joining those two materials with laser AM poses a serious, multifaceted challenge. Bi-layered specimens of tungsten on Eurofer97 were printed using LPBF and DED; formation of intermetallic phases at the interface and the resulting stress/strain field was studied using synchrotron X-Ray Diffraction and Neutron Bragg Edge Imaging.

10:40 AM  
Compositionally Graded Transition from Tungsten to Ferritic-Martensitic Steels via Directed Energy Deposition: Deniz Ebeperi1; Adam Bebak1; Raiyan Seede1; Austin Whitt1; Ibrahim Karaman1; Raymundo Arroyave1; Alaa Elwany2; 1Texas A&M University Department of Materials Science and Engineering; 2Texas A&M University Department of Industrial & Systems Engineering
     W-armored, reduced activation ferritic-martensitic steel structured plasma facing components (PFCs) are reliable and cost-effective candidates for fusion power plant divertors. Directed energy deposition (DED) enables the fabrication of functionally graded materials based on chemical composition, microstructure, and texture, thanks to its ability to deposit multiple alloys simultaneously.In this study, we demonstrated the capability of DED for fabricating fusion-relevant materials with no porosity and cracking, maintaining the structural integrity. We developed a framework for optimizing the processing conditions of each alloy, generated processability maps and fabricated a dense, multilayered, linear compositional gradient from W to GR91 steel, using V-based and Fe-based alloys as transition elements. Challenges for joining alloys with different thermomechanical properties were discussed and solutions were proposed. Effect of processing parameters on part quality was investigated. Microstructural characterization and mechanical testing at elevated temperatures were conducted.

11:00 AM  
Investigation into the Effect of Recrystallization and Microstructure Control on the Properties of GammaPrint™-1100, a High-γ’ crack-resistant Ni-base Superalloy for 3D-printed Parts in Gas Turbines: Ning Zhou1; Stephane Forsik1; Austin Dicus1; Tao Wang1; Gian Colombo1; QQ Ren2; Jonathan Poplawsky2; Mario Epler1; 1Carpenter Technology Corporation; 2Oak Ridge National Laboratory
     GammaPrint™-1100 is a new crack-resistant high-γ’ superalloy developed by Carpenter Technology for 3D-printed parts in gas turbines. In the fully heat-treated condition, the alloy generates 1100 MPa Ys at 760 °C with a hot ductility in excess of 5 El%, and a stress rupture life of 100 hours at 207 MPa and 871 °C. These performances were achieved through composition tuning for grain boundary strengthening and γ/γ’ partition coefficient optimization, as well as grain size control during recrystallization. SEM, EBSD and atom-probe tomography techniques were used to characterize the microstructure with a focus on grain boundary carbides, recrystallization and grain size, and their effect on strength and ductility. The stress rupture properties are interpreted in terms of slow-diffusing element partitioning between the γ channels and the γ’ precipitates. The effect of the post processing heat treatment on the microstructure and mechanical properties is also reviewed.

11:20 AM  Cancelled
Laser Powder Bed Fusion of Crack-Free High Gamma Prime Rene 77 Superalloy: Processing, Heat Treatment, Mechanical Properties and Applications: Marcus Lam1; 1Monash University
    Laser powder bed fusion (LPBF) can be difficult for high gamma prime nickel-based superalloys critically needed for high-temperature, high-strength application. In this presentation, we are reporting successful fabrication of a modified Rene77 superalloy (Al + Ti > 6 wt.%) by LPBF in crack-free state. In addition, a novel post heat treatment method resulted in tensile and creep performance surpassing the commonly used IN718 and even the conventional Rene 77 at up to 650⁰C. The massive grain growth rarely seen in LPBF superalloys that enabled by the heat treatment will also discussed in detail. The fracture surfaces at different temperature and loading conditions will also be presented to understand the deformation mechanism. The LPBF process and post treatments were also performed on actual gas turbine components, validating the techniques developed for actual industrial applications.