| Abstract Scope |
Laser shock compression subjects materials to an extreme regime of high quasi-hydrostatic pressure and high strain rates. The mechanisms of plastic deformation in metals whereby dislocations, twins, and phase transitions. Covalently bonded materials, however, have great difficulty in responding by conventional plastic deformation due to the directionality of their bonds. We propose that the shear from shock compression induces amorphization, as observed in Si, Ge, B4C, SiC, olivine ((Mg, Fe)2SiO4), diamond, and perovskite (CaTiO3) and that this is a general deformation mechanism in a broad class of covalently bonded materials. SEM, FIB and TEM are used to characterize microstructure of the shocked targets, and electron diffraction patterns can confirm the crystal structure of materials. Molecular dynamics simulations are effective to study the motions of atoms and molecules in materials. The three-pronged approach, employing experimental, analytical, and computational methods, has enhanced our understanding of the response of materials under extreme conditions. |