About this Abstract |
Meeting |
2022 TMS Annual Meeting & Exhibition
|
Symposium
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Dynamic Behavior of Materials IX
|
Presentation Title |
Amorphization of Covalently-bonded Materials: A Generalized Deformation Mechanism under Extreme Conditions |
Author(s) |
Boya Li, Shiteng Zhao, Bruce Remington, Christopher Wehrenberg, Hye-Sook Park, Eric Hahn, Marc Meyers |
On-Site Speaker (Planned) |
Boya Li |
Abstract Scope |
Laser shock compression subjects materials to an extreme regime of high quasi-hydrostatic pressure and coupled shear stresses for durations of 1-10 nanoseconds. The mechanisms of plastic deformation in metals whereby dislocations, twins, and phase transitions nucleate and propagate at velocities near the sound speed. Covalently bonded materials, however, have great difficulty in responding by conventional plastic deformation to this extreme regime of shock compression due to the directionality of their bonds. We propose that the shear from shock compression induces amorphization, as observed in Si, Ge, B4C, SiC, and olivine ((Mg, Fe)2SiO4) and that this is a general deformation mechanism in a broad class of covalently bonded materials. The crystalline structure transforms to amorphous along regions of maximum shear stress, forming nanoscale shear bands, and thereby relaxing the shear component of the imposed shock stress. This process is preceded by the emission and propagation of a critical concentration of dislocations. |
Proceedings Inclusion? |
Planned: |