Abstract:
Reviewing the previous theories and models developed
for dislocation/dislocations interactions, the relation for the
creep rate is modified for low temperatures suggesting that the
behaviour of stress relaxation rate is logarithmic in nature. A
self-consistent stress relaxation model is discovered for the
accurate measurement of activation energy in relaxation rate
processes. A single barrier stochastic model of low temperature
creep is developed defining dynamic recovery processes; shape
of the dislocation is obtained by force balance equation, then
using computer model the average dislocation velocity is
cal¬
culated showing that it never becomes zero. A new force balance
equation is used. The dislocations move by forming bulge,
and
unzipping tendency increases as the strength of the barrier
increases contradict Foreman and Makin model (68); the average
velocity of dislocations increases with the increase in the
size of the array, but for small size the average velocity for
each array will be different except where it is constant. Also
the dislocations after covering a short distance reach a steady
state velocity due to coupling effect between strong and weak
barriers. Similarly the dislocation jump approaches an average
or steady state velocity after travelling two or three times
the insert distances. The deformation on slip plane is contro¬
lled by the rate of motion of the pileup nearly equal to
velocity of sound.
