It was recalled that, at low temperatures silicon is a brittle material that shatters catastrophically whereas, at elevated temperatures, the behavior of silicon changed drastically over a narrow temperature range and suddenly becomes ductile. This brittle-to-ductile transition was observed in experimental studies, yet its fundamental mechanisms remained unknown. An atomistic-level study was made here of a fundamental event in this transition: the change from brittle cleavage fracture to dislocation emission at crack tips, using the first-principles based reactive force field. By merely increasing the temperature, an abrupt change from brittle cracking to dislocation emission from a crack was observed within a ≈10 K temperature interval.

Atomistic Study of Crack-Tip Cleavage to Dislocation Emission Transition in Silicon Single Crystals. D.Sen, C.Thaulow, S.V.Schieffer, A.Cohen, M.J.Buehler: Physical Review Letters, 2010, 104[23], 235502