Speaker: Jean-François Croteau
Jean-François Croteau obtained his bachelor’s in mechanical engineering from the University of Ottawa, Canada, in 2017 and his PhD from the École Nationale Supérieure de Techniques Avancées (ENSTA) Bretagne, France, in 2021. He is currently working as a Senior Consultant in research and development at KPMG in Montreal, Canada. His research focuses on experimental characterization of the mechanical, microstructural, and forming properties of metals. During his PhD, Jean-François worked at I-Cube Research, a private company with an expertise in high-pulsed powers, on the characterization of high-purity niobium and copper at low to high strain rates for the manufacturing of superconducting radiofrequency (SRF) cavities for CERN’s particle accelerators. He enjoys collaborating and learning from fellow researchers with different expertise and had the opportunity during his PhD to work at CERN, Michigan State University, Imperial College, Arizona State University, the University of Metz, and more.
Abstract
Manufacturing of superconducting radiofrequency (SRF) cavities with high performances is paramount to increase the collision energy in new particle accelerators that will push the limits of fundamental research in particle physics. The use of high-speed sheet forming techniques, such as electro-hydraulic forming, can be beneficial for cavity performances, but requires a detailed understanding of the mechanical properties of the material being deformed and the consequence of the high strain rate on its microstructure.
This seminar focuses on the characterization of high-purity niobium single crystals extracted from a large-grain niobium disk often used to manufacture SRF cavities. Experimental results on the mechanical properties in tension at strain rates of 10-4 to 103 s-1 and on the microstructure (analyzed using SEM, EBSD, TEM, and nanoindentation) of the deformed specimens will be presented. From those results, the effect of crystal orientation and strain rate on the mechanical properties, the crystal rotation, and the dislocation substructures will be discussed.
Ian Pong