Energy dissipation and path instabilities in dynamic fracture of silicon single crystals

Brittle fracture usually proceeds at crack driving forces which are larger than those needed to create the new fracture surfaces. This surplus can lea d to faster crack propagation or to the onset of additional dissipation mec hanisms. Dynamic fracture experiments on silicon single crystals reported h ere show several distinct transitions between different dissipation mechnni sms. Cleavage fracture is followed by the propagation of a faceted crack fr ont, which is finally followed by a path instability and the propagation of multiple cracks. The fracture surface qualitatively corresponds to the mir ror, mist, and hackle morphology of amorphous materials. However, the corre sponding fracture mechanisms, which remain largely unknown in the amorphous materials, can clearly be identified here.