ABSTRACT

The quasicontinuum method is used to simulate three-dimensional Lomer-Cottrell
junctions both in the absence and in the presence of an applied stress. The
simulations show that this type of junction is destroyed by an unzipping
mechanism in which the dislocations that form the junction are gradually
pulled apart along the junction segment. The calculated critical stress
needed for breaking the junction is comparable to that predicted by line
tension models. The simulations also demonstrate a strong influence of the
initial dislocation line directions on the breaking mechanism, an effect that
is neglected in the macroscopic treatment of the hardening effect of junctions.