On the asymmetrical dissociation of Lomer dislocations

Using anisotropic elasticity theory, Korner, Schmid and Prinz have shown that Lomer-Cottrell dislocations in the f.c.c. structure have asymmetrical equilibrium positions. This is also true for the isotropic theory, but in addition it can also be demonstrated in a very simple way that the ratio of the dissociation widths on the two {111} planes is material independent. This result seems to be general even for the anisotropic case. However, careful observations of Lomer dislocations in copper by weak-beam transmission electron microscopy indicate clearly that they are not dissociated.