Materials Science Research Lecture
***Refreshments at 3:45pm in Noyes lobby
Abstract:
Modern metals manufacturing relies on centuries-old techniques that must be revisited for environmental and resource sustainability. To reinvent metals refinement, processing, and shaping of metals at scale requires new insights to systematically connect fundamental science to process design. My group develops a "modern toolbox" of characterization and computer-vision methods to connect fundamental science to sustainable metals manufacturing. My talk will first describe our work developing time-resolved dark-field X-ray microscopy (DFXM) to directly "watch" the motion and interactions of dislocations deep inside metals over ms-fs timescales. I will show how we now use DFXM to directly measure the microscopic origins of plasticity, failure, and annealing – all essential to metals' performance in technology. Shifting gears, I will then describe our applied work focusing on novel microscopes to give important insights to metal additive manufacturing – a new transformative direction for metals fabrication. Laser powder-bed fusion (LPBF) is limited today by uncertainties in connecting the process optimization to the apparently stochastic properties of the printed parts. Operando X-ray radiography has revealed intricate competition between multi-physics phenomena when metals melt and solidify LPBF, but to correlate the melt-pool phenomena to fracture and phase segregation in the solid is often impossible with the μm-resolution limits of radiography. I will present the first LPBF experiments that use the fs-duration pulses available at X-ray free electron lasers (XFELs) with 1012 photons per pulse to enable opportunities for new types of operando microscopy to reveal these critical phenomena during LPBF. Our science and new approaches to studying dislocations, metal additive manufacturing, and processing offer key opportunities to redesign and advance sustainable manufacturing approaches required across industry.
More about the Speaker:
Leora is an Assistant Professor in the Department of Materials Science & Engineering, with a courtesy appointment in Mechanical Engineering, and a term appointment in Photon Science at the SLAC National Accelerator Lab. Leora studies how modern methods can enable new opportunities to update "old-school" materials processing and manufacturing for sustainability. Leora's group works on thrusts in sustainable steelmaking (specifically ironmaking), metal 3D printing, and studies of the fundamental mechanisms underlying properties in materials. For her work, Leora was awarded the LCLS Young Investigator Award and the Sidhu Award from the Pittsburgh Diffraction Society. She was also selected for an Early Career Research Award from the US Department of Energy in 2023, and a Young Investigator Research Program Award from the Air Force Office of Scientific Research in 2023. Before joining Stanford, Leora was a Lawrence Fellow in the Physics Division of Lawrence Livermore National Labs, studying shock waves and high-temperature metallurgy. Leora did her PhD in Physical Chemistry at the Massachusetts Institute of Technology and got her Bachelor of Arts and Master's of Science both in Chemistry at the University of Pennsylvania.