ABSTRACT

The structure and strength of three-dimensional Lomer-Cottrell junctions
are studied using four different models. These models represent increasing
levels of sophistication, with each case including some new physical effect.
The line tension approximation makes use only of the elastic self energy of
the dislocation lines. The edge-screw dislocation dynamics model increases
the sophistication by including the elastic interactions between all of the
dislocation segments. At the next level of sophistication, the nodal
dislocation dynamics method accounts for the dissociation of the core into
partial dislocations. Finally, the quasicontinuum method takes into account
the core effects at the atomic level. The results show that although the line
tension model represents a huge simplification of the physics of dislocations,
it is able to reproduce the equilibrium structure of any type of Lomer-Cottrell
interaction, both in the absence and presence of an externally applied
stress. The pseudo-analytical description can thus be used as a bench mark
for the development of dislocation dynamics simulations.