Dislocation dynamics in the plastic deformation of silicon crystals I. Experiments

Stress‐strain characteristics in silicon crystals are investigated as a function of the temperature, the strain rate, and the initial density of dislocations. Dislocation multiplication in the yield region is also observed by means of etch‐pit technique. Specimens with lower initial densities of dislocations have higher magnitudes of both the upper and the lower yield stresses. This is shown to be related with the activation of the secondary slip systems during yielding. The effective stress is determined by the strain‐rate change technique on the basis of the experimental velocity equation of dislocations. The steady state of deformation where the effective stress is constant with respect to the strain is observed to appear in the deformation stage after stage 0. The density and the velocity of moving dislocations in such steady state are determined as a function of the temperature and the strain rate.