The role of dislocation activities in the brittle-ductile transition in silicon single crystals
To determine the controlling mechanisms in the brittle-ductile transition (BDT) in silicon single crystals, one must identify the conditions for dislocation nucleation at crack tips. In the present study, dislocation nucleation in $\{110\}$$$ oriented silicon is determined experimentally. The specimens are first statically loaded at high temperatures, and then fractured at room temperature. It is found that an increase in fracture toughness is associated with crack-tip dislocation activity during the high-temperature static loading. The loading condition at the onset of fracture-toughness increase corresponds to the one for dislocation nucleation at the high temperatute. The results indicate that dislocations can nucleate at temperatures well below the commonly observed BDT temperature, indicating that the BDT in silicon is governed by dislocation mobility rather than dislocation nucleation.
Applied Mechanics, Engineering, Materials Science
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign