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Seminar on Mechanical Science and Bioengineering
205th
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November 12, 2024 13:30-14:30 Seminar Room C (C419) |
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In Japanese | |
204th
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November 1, 2024 10:30-11:30 A442 |
In Japanese | |
203rd
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December 3, 2024 11:00-12:00 Seminar Room C |
In Japanese | |
202nd
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October 25, 2024 14:00-15:00 Seminar Room J114 |
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.anisms of MPEAs. | |
Dr. In-Suk Choi
Department of Materials Science and Engineering, Seoul National University |
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201st
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October 11, 2024 13:30-14:30 Room B401 |
In Japanese |