Spotlight Speakers
Dr. Katerina Christofidou
Exploiting Invariant Reactions Towards the Design of Nickel-Base Superalloys for Laser Powder Bed Fusion
Additive manufacturing (AM) in aerospace has faced persistent challenges with solidification cracking, especially in Ni-based superalloys with high γ′ content. To address this, this work investigates the potential of exploiting invariant reactions, such as eutectics, to narrow the solidification window and mitigate cracking issues. γ-γ′-MC carbide eutectic alloys, developed in the 70s and 80s, present a promising foundation to test this hypothesis due to their unique microstructural stability.
In this study, two of these eutectic alloys—Cotac-74 and Cotac-744— were examined and evaluated for their suitability for AM, particularly via laser powder bed fusion (L-PBF). Using laser pass tests and L-PBF processing, the cracking resistance and microstructural evolution of these alloys was assessed and benchmarked against the conventional superalloy CM247LC.
The results from these trials serve as a basis for further optimization of the alloy chemistry as well as highlighting areas for additional process development for spatial tailoring of component performance. Our ongoing work seeks to refine the performance of these materials, manipulate microstructures, and tailor properties for high-temperature, high-performance applications. This research opens up pathways for the development of more resilient superalloys designed specifically for additive manufacturing.
Katerina (Kathy) Christofidou is Professor in Digital and Sustainable Metallurgy at the University of Sheffield, where she also leads the Advanced Metals Processing research area for the Henry Royce Institute, the UK’s National Institute for Advanced Materials Research. She holds a PhD in Metallurgy from the University of Cambridge and an MEng degree in Aerospace Materials Engineering from Imperial College London. Her research bridges high performance alloy design and advanced manufacturing, focusing on accelerated methods of alloy development and high throughput testing including design for manufacture of high-performance engineering components. Throughout her career she has worked at the interface between industry and academia, delivering meaningful metallurgical insights, and was recognised in 2022 by the Institute of Materials, Minerals and Mining with the Grünfeld medal for the application of metals to industry.
Dr. Krishna Kumar Saxena
The Future of Micro and Precision Electrical Machining Research: Going Beyond Holes and Steels
KU Leuven has a long-standing research history in the field of micro and precision electrical machining. This talk will therefore highlight the newer research activities in electrical micromanufacturing including the in-house developed hybrid laser-ECM technology, AFM-ECM technology, micro-EDM technology and related applications towards advanced materials processing, precision components and ceramic injection moulding. The talk will introduce a mix of fundamental and production-oriented research in line with mechanism-based understanding towards advancing state-of-the-art in electrical manufacturing technologies. The presentation will highlight research advances beyond traditional trends of drilling holes and machining steels in the community. The talk will also highlight the future prospects where electrical micromanufacturing can compete well with other competitive technologies especially for the application cases which are still very difficult with other machining technologies. This research track has received funding from EU H2020, FWO (Belgian Flemish National Science Foundation) and KU Leuven funds so far.
Krishna Saxena is currently working as a senior FWO postdoctoral fellow in department of mechanical engineering at KU Leuven, Belgium after serving first term as FWO junior postdoctoral fellow. He is also serving as a lecturer at KU Leuven Campus Bruges and Geel. During Nov. 2022 – Feb. 2023, he worked as a visiting assistant professor/visiting FWO postdoc at department of precision engineering at University of Tokyo, Japan. He obtained his Ph.D. degree as a Marie Curie Early Stage Researcher (EU H2020 Microman) in mechanical engineering from KU Leuven, Belgium, in 2020 and thereafter worked as a postdoctoral research engineer on the EU project PROSURF. His doctoral research was sponsored by two European projects: European Marie Curie ITN H2020 project ‘MICROMAN’ and EU Factories of Future project ‘PROSURF’ while receiving trainings on different manufacturing and metrology aspects at European/UK universities (U-Bremen, PoliMi, DTU, U-Bradford, U-Nottingham, U-Strathclyde). He has also conducted short research stays at TU Chemnitz, Germany during his doctoral research. He carried out his master thesis research exchange at Institute of metal forming technology, University of Stuttgart, Germany (2016) while pursuing masters at Indian Institute of Technology Gandhinagar and subsequently also worked as a researcher at the Department of Mechanical Engineering, Centre for Advanced Composite Materials, University of Auckland, New Zealand (2015). He has 8+ years of research experience in various aspects of subtractive non-traditional manufacturing technologies.
Dr. Sarah Wolff
Repurposing, Reusing, and Recycling Feedstocks for Laser Additive Manufacturing
The overarching objective of this talk is to discuss how the characteristics of repurposed, reused, and recycled feedstock influence melting and solidification in laser additive manufacturing (AM) in pursuit of a circular economy and industrial symbiosis. The scope of this talk will focus on the laser directed energy deposition (L-DED) process, which is an AM process for near-net shape component fabrication, re-manufacture, and repair. Though repurposing, reusing, and recycling feedstock for the L-DED process can minimize environmental impact of metals production, there may be contaminants in the feedstock that may alter production and the final component. These contaminants include oxidation and ”tramp” elements, or impurities, that may result in the degradation of material properties. On the other hand, the characteristics of reused and recycled material, including chemical composition and morphology, interact with laser AM processes for unique melting and solidification pathways not observed with atomized feedstock. This talk discusses the influence of tramp elements and feedstock morphology on melting, oxidation, particle segregation, intermetallic phase formation, and overall microstructure in AM components. The approaches to reveal these influences include in situ and operando experimental methods, including high-speed optical and synchrotron X-ray imaging and diffraction to capture the phase transformations during solidification in real-time at multiple scales. This talk will also discuss the vision for the future of laser manufacturing, including how processes can align with a circular economy, industrial symbiosis, and a sustainable world.
Sarah Wolff is an assistant professor in the mechanical and aerospace department at the Ohio State University. Her previous roles include an assistant professorship in the industrial and systems engineering department at Texas A&M University and an Enrico Fermi Fellow at Argonne National Laboratory. She graduated from Northwestern University in 2018 with a PhD in mechanical engineering. She was awarded the 2022 SME Sandra L. Bouckley Outstanding Young Manufacturing Engineer. Sarah Wolff is a CIRP research affiliate, an associate editor for Additive Manufacturing Letters, and on the editorial board for International Journal of Machine Tools and Manufacture. She is also active in broadening participation for women in manufacturing and works on international educational opportunities for graduate students.
Dr. Katrin Wudy
Beam Shaping the Next Innovation Leap in Powder Bed Fusion of Metals?!
Can laser beam shaping address the critical obstacles in laser-based powder bed fusion of metals (PBF-LB/M)? PBF-LB/M currently faces challenges such as limited production speed and process anomalies, which may induce part defects. While Gaussian beams are the standard in PBF-LB/M, they induce melt pools prone to spatter formation and keyholing, resulting in keyhole porosity.
At the Professorship of Laser-based Additive Manufacturing, we answer the research question on how spatial and temporal beam shaping in PBF-LB/M affects the process signature and resulting part properties. This talk will highlight the integration of beam shaping with advanced monitoring methods, aiming to create a toolbox for first-time-right manufacturing in PBF-LB/M. Our beam-shaping strategies encompass temporal scanner-based techniques and spatial beam shaping with spatial light modulators, acousto-optic deflectors, and a multi-core fiber concept. Additionally, we are exploring innovative monitoring technologies, such as integrating sphere measurements and multi-spectral imaging to analyze the effect on the process signature.
This presentation will evaluate spatial and temporal beam shaping technologies based on their complexity, design freedom, and performance in PBF-LB/M. This is supported by novel monitoring techniques that measure the absolute temperature during exposure and quickly detect the sweet spot for processing. By combining these methods, we aim to achieve a more stable melt pool and increase production speed, ultimately reducing resource and energy consumption. In the future, beam shaping could be used to tailor the microstructure of parts within a single process or to manufacture hard-to-weld materials, opening up entirely new applications for PBF-LB/M.
Katrin Wudy’s research focuses on laser-based additive manufacturing techniques with both plastics and metals, covering the entire process chain from material development and innovative process strategies to process monitoring and quality management in additive manufacturing. Since June 2024, she has been an Associate Professor for Laser-based Additive Manufacturing at the Technical University of Munich (TUM), one of Europe’s leading universities, and a member of the TU9 Universities of Technology Excellence in Engineering and Science in Germany. Prior to this role, she was Assistant Professor at TUM. Katrin Wudy earned her PhD in Mechanical Engineering from Friedrich-Alexander-University Erlangen-Nuernberg (FAU), focusing on the aging behavior of Polyamide 12 in selective laser sintering in 2017. At FAU, she managed the Collaborative Research Center 814 (SFB 814) – Additive Manufacturing and was a group leader at the Institute of Polymer Technology. Katrin Wudy is actively involved in various scientific societies and committees, including the steering committee of TUM. Additive and in the selection committee for the Allocation of Humboldt Research Fellowships. Her contributions include overseeing the Master’s program in Mechatronics, Robotics, and Biomechanical Engineering. Katrin Wudy’s extensive expertise positions her as a leader in laser-based additive manufacturing.