Amorphization and nanocrystallization of silicon under shock compression

High power pulsed laser driven shock compression and recovery experiments on (001) silicon unveiled remarable structural changes above a pressure threshold. Two distinct amorphous regions were identified:(a) a bulk amorphous layer close to the surface and (b) amorphous bands initially alligned with {111} slip plabnes. Further increase of the laser energy leads to the recrystallization of amorphous silicon into nanocrystals with high concentration of nanotwins. This amorphization is produced by the combined effect of high magnitude hydrostatic and shear stresses under dynamic shock compression. Shock-induced defects play a very important role in the onset of amorphization. Calculations of the free energy changes with pressure and shear, using the Patel-Cohen methodology, are in agreement with the experimental results. MD simulation corroborates the amorphization, showing that it is initated by the nucleation and propagation of partial dislocations. The nucleation of amorphization is analyzed qualitatively by classical nucleation theory.

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Recommended citation: S. Zhao, E.N. Hahn, B. Kad, B.A.Remington, C.E. Wehrenberg, E.M.Bringa, M.A. Meyers. (2015). “Shock-induced amorphization in silicon carbide.” Acta Materialia. 103(519-533).