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Published on: January 16, 2019
Threshold crack speed controls dynamical fracture of silicon single crystals
Markus J Buehler1, Harvey Tang, Adri C T van Duin
1Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 1-272, Cambridge, MA 02139, USA. mbuehler@MIT.EDU
Abstract:
Fracture experiments of single silicon crystals reveal that after the critical fracture load is reached, the crack speed jumps from zero to approximately 2 km/sec, indicating that crack motion at lower speeds is forbidden. This contradicts classical continuum fracture theories predicting a continuously increasing crack speed with increasing load. Here we show that this threshold crack speed may be due to a localized phase transformation of the silicon lattice from 6-membered rings to a 5-7 double ring at the crack tip.
