Our research on metal additive manufacturing, or 3D printing, centers on innovative design for multi-functionality in engineering applications, high-throughput experiments for fundamental alloy discovery, and microstructural control for qualification and certification of engineering components.
Metal additive manufacturing, at this time, lends itself to lower volume and higher cost components. Future trends and research will increase the volume and lower the cost in this rapidly growing sector. New discoveries on material properties, metamaterials, and light-weighting are within our reach.
Defect control during processing is an important safety feature for the fabrication process. Our research looks at a variety of methods to promote safety in the additive process.
Research Focus Areas
Manufacturing Design
-Machine learning for process optimization
-Topology optimization
-Lightweighting
-Hierarchical structures
Alloy Design
-High-throughput experimentation and characterization
-High entropy alloys
-Bulk metallic glasses
-Functionally-graded materials
-Controlled solidification
-Phase transformation
EXPLORING HIGH-ENTROPY ALLOYS FOR FUEL CLADDING
We work with collaborators to develop novel fuel cladding materials, specifically high-entropy alloys (HEAs), for next-generation sodium-cooled fast reactors (SFRs). Researchers explore HEA composition by additively manufacturing samples using different combinations of elemental powders. Such a technique will allow for an array of different alloys to be produced in a single session as opposed to traditional fabrication techniques which are much more time consuming. This research is being conducted by Michael Moorehead, a PhD student advised by Professor Adrien Couet in the UW-Madison Engineering Physics Department working in collaboration with the Alloy Design and Development Lab.
UNDERSTANDING MICROSTRUCTURAL RESPONSE
Scientists work on characterizing the microstructure of additively manufactured metals across length scales to determine the influence of processing parameters on structure and mechanical properties. Future research will aim to develop a more complete understanding of how microstructural variations affect mechanical response from the nano to macroscales, with an emphasis on mesoscale characterization and modeling techniques.
IMPROVING PERFORMANCE OF STRUCTURAL MATERIALS
Research on bulk amorphous glasses has been carried out for many years because these materials possess superior properties. The low-cost high-strength magnesium (Mg) and its alloys have attracted significant interest. As the lightest metallic structural materials, Mg-based alloys have great potential for use in aerospace, automotive, consumer electronics, medicine, sport, military equipment and hydrogen storage for clean energy. To improve properties of Mg, it is necessary to transform hcp Mg into stable bcc Mg. For this purpose, Celal Kursun, a postdoctoral researcher has carried out the studies on synthesis and characterization of novel Mg-based alloys.
ACCELERATING MATERIALS DEVELOPMENT TO ADVANCE CLEAN ENERGY PRODUCTION
Dan Thoma and a group of University of Wisconsin-Madison researchers received a $1.8 million grant to develop new materials for multiple uses, including the ability to withstand the corrosive environment within a molten salt nuclear reactor.
LIGHTWEIGHTING IN METAL ADDITIVE MANUFACTURING
Metal additive manufacturing techniques such as Direct Metal Laser Sintering (DMLS) and Directed Energy Deposition (DED) allow for complex geometry fabrication of metal parts, a capability that is of special interest from a design point of view. Means to minimize material consumption, build time and consequently, manufacturing costs is constantly being sought after in Additive Manufacturing (AM). Lightweight design is considered one of the most promising methods to achieve this objective.
3D PRINTING WITH STAINLESS STEEL
Researchers developed Bucky Badger figurines which were 3D printed by selective laser melting (SLM) of a power bed. In this process, support scaffolding is designed to provide consistent heat transfer during build-up. Scaffolding designs are being investigated to reduce material and consumption cost. The effects of process parameters and heat treatment on the microstructure of metal is also being investigated to achieve better control over microstructure evolution throughout the printing process.
ANALYZING 3D PRINTED MICROSTRUCTURES
Our scientists conduct analyses of a variety of metallographic samples, including 316 stainless steel, aluminum, and maraging steel. One area of research focuses on the production of metal samples via the Optomec LENS (Laser Engineered Net Shaping) MR7 3D printer, and how the print process affects the microstructure of the material. In addition, we investigate how varying just one of many explicit individual parameters of the machine will affect the microstructure and mechanical properties of the material. Such adjustable parameters include laser power and powder feed rate. These objectives are being investigated by research assistant Bailey Kuehl, an undergraduate student pursuing a degree in the Materials Science and Engineering Department at the University of Wisconsin-Madison. For future research, Bailey will work to predict how varying certain individual parameters will affect the microstructure of stainless steel and other metals. Bailey hopes this research will result in more practical use of parts made by metallographic 3D printers in industries such as biomedical, renewable energy, infrastructure resiliency, and many more.
USING MACHINE LEARNING TO DEVELOP NEW ALLOYS
The high-throughput fabrication and characterization techniques of additively manufactured metals is an area of emphasis in the ADD Lab. Specifically, the effects of SLM processing parameters will be assessed on the basis of density, microstructures, and performance. Ankur Agrawal aims to develop processing maps and solidification maps for the SLM process using high-throughput techniques. This research is useful for microstructural designing of as-fabricated samples and will improve the performance of additively manufactured components. Ankur also aims to couple his work with modeling and machine learning techniques to understand the fundamentals of laser-powder interaction and to predict the optimal processing conditions for new alloys.
DESIGNING NEW MICROSTRUCTURES
Studying the use of metal additive manufacturing (AM) to design novel microstructures in alloys is one aim of our research. With applications in structural materials for extreme environments such as the ones encountered in power plants, this research could lead to big societal impact. Enhanced microstructural control could help scientist develop and discover superior components which are more resistant to degradation. For example, the directed energy deposition AM technique enables us to fabricate functionally-graded components, with different microstructures, and properties, at the surface and in the bulk of the component.
Publications
- “Influence of Solidification-Induced Sub-Granular Structures on Radiation-Induced Swelling in an Additively-Manufactured Austenitic Stainless Steel,” G. Meric de Bellefon, et al. J. of Nuclear Materials, https://www.sciencedirect.com/science/article/pii/S0022311519305343, 523, 291 (Sept. 2019)
- “An Investigation into the Challenges of Using Metal Additive Manufacturing for the Production of Patient-Specific Aneurysm Clips,” B.J. Walker, et al., J. of Medical Devices, https://asmedigitalcollection.asme.org/medicaldevices/article/13/3/031009/727256/An-Investigation-Into-the-Challenges-of-Using, 13,3 031009 (Sept. 2019)
- “High-Throughput Synthesis of Mo-Nb-Ta-W High-Entropy Alloys via Additive Manufacturing,” M. Moorehead, et al. Materials Design, https://www.sciencedirect.com/science/article/pii/S0264127519307968, 187 108358 (Feb. 2020).
- “Experimental Validation of Topology Optimized, Additively Manufactured SS316L Components,” B. Rankouhi, et al., Materials Science and Engineering A. https://www.sciencedirect.com/science/article/pii/S0921509320301386, 776,3 139050 (March 2020)
- “A Comparison of 316L Stainless Steel Parts Manufactured by Directed Energy Deposition using Gas Atomized and Mechanically Generated Feedstock,” M. Jackson, et al., CIRP Annals Manufacturing Technology, (April 2020).
- “Production of Mechanically-Generated 316L Stainless Steel Feedstock and its Performance in Directed Energy Deposition Processing as Compared to Gas-Atomized Powder” M.A. Jackson, A. Kim, Jacob A. Manders, J. D. Morrow, D.J. Thoma, F.E. Pfefferkorn, https://www.sciencedirect.com/science/article/abs/pii/S1755581720300638?via%3Dihub Manufacturing Science and Technology (accepted, 2020).
- “High-throughput Experimentation for Microstructural Design in Additively Manufactured 316L Stainless Steel” A. Kumar Agrawal, G. Meric de Bellefon, D.J. Thoma, Materials Science and Engineering https://www.sciencedirect.com/science/article/abs/pii/S092150932030914X, AA793139841 (2020).
- Origins of Dislocation Structures in an Additively Manufactured Austenitic Stainless Steel 316L” K.M. Bertsch, B.M. de Bellefon, B. Kuehl, D.J. Thoma Acta Materialia, https://www.sciencedirect.com/science/article/abs/pii/S1359645420305796, 19919-33 (2020).