MaWi-Kolloquium (Hybrid)

Prof. In-Suk Choi

Department of Materials Science and Engineering
Seoul National University

Electron-Beam Induced Athermal Deformation: A Novel Understanding for Viscoplastic Deformation and Mechanical Amorphization of Amorphous and Crystalline Silica

Amorphous silica, typically brittle, can undergo viscoplastic deformation at elevated temperatures. In this study, we highlight the possibility of achieving precise nanoscale mechanical shaping of amorphous silica through electron-matter interactions, without the need for heating. We found that ductile plastic deformation and densification can be induced athermally by focused scanning electron beams at low acceleration voltages. Our simulations indicate that the extent of deformation is governed by the interaction volume, where inelastic scattering occurs. Moreover, we demonstrated that electron beam irradiation can dramatically facilitate solid-state mechanical amorphization of crystalline α-quartz at room temperature, a process that usually demands high pressure. Microstructural examinations and atomic-scale simulations suggest that this is attributed to the uniformly distributed delocalized electrons, introduced by the electron beam excitation, collectively moving like anions situated between the positively charged silicon ions, effectively mitigating the repulsive forces within the distorted atomic structures. This research not only deepens our comprehension of electron-matter interactions but also unveils a new pathway for mechanical forming and processing of glass and ceramic materials.

[1] E-beam-enhanced solid-state mechanical amorphization of α-quartz: Reduced deformation barrier via localized excess electrons as network modifiers, Materials Today 66, 62, 2023.

[2] Athermal glass work at the nanoscale: Engineered electron-beam-induced viscoplasticity for mechanical shaping of brittle amorphous silica, Acta Materialia 238, 118203, 2022.

Dr. Choi is a professor in the Department of Materials Science and Engineering at Seoul National University. He earned a BS from Seoul National University, an MS from Stanford University, and a Ph.D. from MIT in Materials Science and Engineering. After completing postdoctoral research at the Karlsruhe Institute of Technology in Germany, Dr. Choi worked as a Principal Research Scientist at the Korea Institute of Science and Technology (KIST) before joining Seoul National University in 2018. He currently serves as a member of several editorial boards for domestic and international journals. His current research focuses on developing advanced structural materials for extreme conditions and interdisciplinary projects.

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