Author: Lee, Seok-Woo

Zhongyuan’s carbon pillar work is published Nature Comm!

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Zhongyuan’s carbon pillar work is published Nature Comm! Many congratulations on this great achievement!

This work reports the discovery of ultrahigh strength of nanoporous amorphous carbon nanopillars, which are fabricated through self-assembly, nanoimprinting, and carbonization processes. This material is easily scalable up to centimeter scale, providing a strong potential to develop advanced structure material across the wide length scale.

 

Seok-Woo introduced MSE to high school students at E2 program!

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[Explore Engineering (E2) 2024 Lecture for high school students]

Explore Engineering 2024 PPT Slide [PPT file]

Seok-Woo Lee, “Make a new material that changes the world,” (2024) [Working_Draft] – This is the book that introduces Materials Science and Engineering to high schoolers!

Invited Talk at Seoul National University and Yonsei University

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Seok-Woo gave the invited presentation at (1) Materials Science and Engineering at Seoul National University and (2) Mechanical Engineering at Yonsei University in South Korea.

The title of presentation was “Superelasticity of ThCr2Si2-structured Intermetallic Compounds via Lattice Collapse and Expansion”. This talk summarized our group’s 8 years research on ThCr2Si2-structured Intermetallic Compounds.

The presentation slides can be downloaded here.

Lee group rocked the TMS 2024 (Orlando, FL)!

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Lee group rocked the TMS 2024 (Orlando, FL)! There were FIVE oral presentations! Everyone did a great job!!!

  • Alexander Horvath, “Tension-compression asymmetric behavior of screw dislocation in body-centered-cubic metal nanopillars,” Symposium: Mechanical Behavior at the Nanoscale VII, 4:10PM-4:30PM, 03/04/2024, Room: Manatee Spring I
  • Seok-Woo Lee, “Micro-tensile behavior of niobium single crystals at cryogenic temperatures,” Symposium: Nanostructured Materials in Extreme Environments II, 5:20PM-5:40PM, 03/05/2024, room: Bayhill 19
  • Zhognyuan Li, “Nanoporous amorphous carbon nanopillars with lightweight, near-theoretical strength, large fracture strain, and high damping capability,” Symposium: Mechanical Response of Materials Investigated through NovelIn-situ Experiments and Modeling, 2:20PM-2:40PM, 03/06/2024, room: Barrel Spring I
  • Kyrus Tsai (Mark Aindow’s group, Seok-Woo and Jay were co-authored!), “The Effects of Molybdenum Segregation on Mechanical Behavior in Maraging Steel Processed by Wire Directed Energy Deposition,” Symposium: High Performance Steels, 03/06/2024, 4:55PM-5:15PM, room: Bayhill 31
  • Zachary Arenella, “Grain Size Effect on Microstructural Evolution in Nanocrystalline MgAl2O4 under Nanoindentation,” Symposium: Mechanical Behavior at the Nanoscale VII, 11-11:20AM, 03/07/2024, room: Manatee Spring I

 

<Dinner with Alex and Zhongyuan at Disney Spring>

<Alex’s presentation>

<Zack’s presentation>

<Dinner with Prof. William Nix (Seok-Woo’s PhD advisor) and his former PhD students>

 

 

Seok-Woo gave an invited talk at EMA 2024.

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Seok-Woo gave an invited talk at the EMA (Electronic Materials and Applications) meeting (February 13-16) organized by the American Ceramic Society (ACers)!

AcerS EMA 2024 (Denver, CO)

  • Seok-Woo Lee, “Grain size dependence of mechanical properties of nanocrystalline magnesium aluminate MgAl2O4” (invited talk) – Symposium 5: Grain Boundary Structure and Mechanical Properties I, 2-2:30PM, 02/15/2024, room Colorado G.
    Abstract: To develop transparent materials with superior mechanical properties, nanocrystalline magnesium aluminate (MgAl2O4) spinel with grain sizes ranging from 3.7 to 80 nm has been synthesized by environmentally controlled pressure assisted sintering. In this study, we investigated the microstructure and grain size dependence of the mechanical properties of nanocrystalline MgAl2O4by performing transmission electron microscopy, nanoindentation, uniaxial micropillar compression, and micro-cantilever bending.Electron microscopy confirmed that the environmentally controlled pressure assisted sintering technique produces a nearly fully dense grain structure with a porosity of less than 1% in larger grain-sized ceramics and observably pore-free grain structures in the smaller grain-sized ceramics. Mechanical characterization revealed that nanoindentation hardness, compressive fracture strength, and fracture toughness each exhibit distinct grain size dependence. Our experimental results and numerical analyses point to a change in dominant strain accommodating mechanisms from dislocation-based plasticity to shear banding as the grain size is reduced, as previously suggested by the literature. Practical implications of the change in strain accommodation mechanisms manifest as the emergence of indentation size effect, weak grain size dependence of hardness and strength, and a ∼2-fold increase in apparent fracture toughness for the smaller grain-sized ceramics.