Leora studies how modern methods can enable new opportunities to update "old-school" materials processing and manufacturing for sustainability. This includes designing new microscopes and using them to get a deeper view into the extraction, forming, and functional properties of metallic materials. Leora's group works on thrusts in sustainable steelmaking (specifically ironmaking), metal 3D printing, and studies of the fundamental mechanisms underlying properties in materials.
Leora is an Assistant Professor in the Department of Materials Science & Engineering, with a courtesy appointment in Mechanical Engineering, a term appointment in Photon Science at the SLAC National Accelerator Lab, and an appointment as a Precourt Center Fellow. Before coming to Stanford, Leora was a Lawrence Fellow in the Physics Division of the Physics and Life Sciences Directorate at Lawrence Livermore National Labs, where she developed the tools to study time-resolved defect dynamics in bulk materials -- giving new insights into long-standing problems in materials science. Leora did her PhD in Physical Chemistry with Prof. Keith Nelson at MIT, where she demonstrated how shock waves initiate chemistry in RDX that couples to deformations in unique ways that enhance the sensitivity. Leora did her BA and MSc in Chemistry at the University of Pennsylvania.
Gabilan Fellow, Stanford University (2021 - Present)
Terman Fellow, School of Engineering, Stanford (2021 - Present)
Courtesy Appointment, Mechanical Engineering, Stanford (2021 - Present)
Precourt Center Fellow, Precourt Center for Renewable Energy, Stanford (2021 - Present)
Term Appointment, Photon Science, SLAC (2021 - Present)
Current Research and Scholarly Interests
The Dresselhaus-Marais research group develops new methods to update 19th-century manufacturing processes with modern approaches. Our approach focuses on a holistic view of metals fabrication, from the mining and extraction of ores into metals to a deep look at how specific microstructural features (e.g. dislocations and grain boundaries) during the forming and forging give rise to mechanical and thermal properties we can tune or print.
To get this deep view of modern processing, we develop and use new optical/X-ray and analytical tools to reveal how imperfections deep inside materials instigate the dynamics that transform them. Spanning length- and time-scales from bonds breaking at single atoms through long-duration dwell times in 100-m tall blast furnace reactors, these defect dynamics define complex high-dimensional problems that are difficult to reconcile at intermediate scales in order to predict or understand a material's behavior and chemistry. To address this challenge, we develop new types of time-resolved experiments aimed at the elusive "mesoscale" to directly visualize how large populations of subsurface defects drive them. With these new approaches, we tackle fundamental studies of how temperature drives materials, and applied problems.
Our applied work focuses on two important steps of the supply chain: metals extraction and metal forming. Most metals extraction processes have been perfected for centuries to millennia, but are done today at scales that make our effective processing strategies unsustainable. In cases like steel (8% of global CO2 emissions), this arises from coal-intensive steps that produce Gigatons of CO2 per year that contribute significantly to climate challenges. For metals like lithium and rare earth elements, our present mining and extraction strategies simply cannot reach a high enough throughput to sustain our current demand for the elements, making them Critical Materials. My group studies how an updated multiscale characterization and modeling approach can enable key opportunities to advance these fields.
- Defects and Disorder in Materials
MATSCI 183 (Spr)
- Defects and Disorder in Materials
MATSCI 213 (Spr)
- Kinetics of Materials Synthesis
MATSCI 145 (Aut)
- Materials Science Colloquium
MATSCI 230 (Aut, Win, Spr)
Independent Studies (7)
- Directed Studies in Applied Physics
APPPHYS 290 (Aut, Win, Spr, Sum)
- Engineering Problems
ME 391 (Win, Spr)
- Experimental Investigation of Engineering Problems
ME 392 (Spr)
- Master's Research
MATSCI 200 (Aut, Win)
- Ph.D. Research
MATSCI 300 (Aut, Spr)
- Undergraduate Independent Study
MATSCI 100 (Aut)
- Undergraduate Research
MATSCI 150 (Aut)
- Directed Studies in Applied Physics
- Prior Year Courses
An automated approach to the alignment of compound refractive lenses
JOURNAL OF SYNCHROTRON RADIATION
2022; 29: 947-956
Compound refractive lenses (CRLs) are established X-ray focusing optics, and are used to focus the beam or image the sample in many beamlines at X-ray facilities. While CRLs are quite established, the stack of single lens elements affords a very small numerical aperture because of the thick lens profile, making them far more difficult to align than classical optical lenses that obey the thin-lens approximation. This means that the alignment must be very precise and is highly sensitive to changes to the incident beam, often requiring regular readjustments. Some groups circumvent the full realignment procedure by using engineering controls (e.g. mounting optics) that sacrifice some of the beam's focusing precision, i.e. spot size, or resolution. While these choices minimize setup time, there are clear disadvantages. This work presents a new automated approach to align CRLs using a simple alignment apparatus that is easy to adapt and install at different types of X-ray experiments or facilities. This approach builds on recent CRL modeling efforts, using an approach based on the Stochastic Nelder-Mead (SNM) simplex method. This method is outlined and its efficacy is demonstrated with numerical simulation that is tested in real experiments conducted at the Advanced Photon Source to confirm its performance with a synchrotron beam. This work provides an opportunity to automate key instrumentation at X-ray facilities.
View details for DOI 10.1107/S1600577522004039
View details for Web of Science ID 000824201700003
View details for PubMedID 35787560
View details for PubMedCentralID PMC9255570
- X-ray free-electron laser based dark-field X-ray microscopy: a simulation-based study JOURNAL OF APPLIED CRYSTALLOGRAPHY 2022; 55: 112-121
In situ visualization of long-range defect interactions at the edge of melting.
2021; 7 (29)
Connecting a bulk material's microscopic defects to its macroscopic properties is an age-old problem in materials science. Long-range interactions between dislocations (line defects) are known to play a key role in how materials deform or melt, but we lack the tools to connect these dynamics to the macroscopic properties. We introduce time-resolved dark-field x-ray microscopy to directly visualize how dislocations move and interact over hundreds of micrometers deep inside bulk aluminum. With real-time movies, we reveal the thermally activated motion and interactions of dislocations that comprise a boundary and show how weakened binding forces destabilize the structure at 99% of the melting temperature. Connecting dynamics of the microstructure to its stability, we provide important opportunities to guide and validate multiscale models that are yet untested.
View details for DOI 10.1126/sciadv.abe8311
View details for PubMedID 34261647