Shock-induced amorphization in silicon carbide
S Zhao and R Flanagan and EN Hahn and B Kad and BA Remington and CE Wehrenberg and R Cauble and K More and MA Meyers, ACTA MATERIALIA, 158, 206-213 (2018).
While silicon carbide (SiC) has been predicted to undergo pressure- induced amorphization, the micro structural evidence of such a drastic phase change is absent as its brittleness usually prevents its successful recovery from high-pressure experiments. Here we report on the observation of amorphous SiC recovered from laser-ablation-driven shock compression with a peak stress of approximately 50 GPa. Transmission electron microscopy reveals that the amorphous regions are extremely localized, forming bands as narrow as a few nanometers. In addition to these amorphous bands, planar stacking faults are observed. Large-scale non-equilibrium molecular dynamic simulations elucidate the process and suggest that the planar stacking faults serve as the precursors to amorphization. Our results suggest that the amorphous phase produced is a high-density form, which enhances its thermodynamical stability under the high pressures combined with the shear stresses generated by the uniaxial strain state in shock compression. (C) 2018 Published by Elsevier Ltd on behalf of Acta Materialia Inc.
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