Dislocation arrangements in single crystalline silicon fatigued in tension/compression

Preliminary results of low-cycle fatigue experiments at high temperatures on [123] silicon single crystals are reported. The effects of temperature (from 1073 to 1373 K), plastic strain rate (from 5 × 10−5 to 5 × 10−3 s−1) and plastic strain amplitude (10−3 and 5 × 10−3) on the mechanical behaviour are investigated. At low temperature and high strain rate, fracture took place after about 100 cycles, while saturation of the maximum stress could be reached at higher temperatures and lower strain rates. Transmission electron microscopy (TEM) observations reveal that a cellular arrangement of dislocations is associated with the latter case while loop-patches are characteristics of the former.