Dissociated dislocations in Ni: a computational study

A systematic computational study of the behavior of a (1/2)〈110〉 dissociated screw dislocation in fcc nickel is presented, in which atomic interactions are described through an embedded-atom potential. A suitable external stress is applied on the system, both for modifying the equilibrium separation distance d and moving the dislocation complex. The structure of the dislocation and its corresponding changes during the motion are studied in the framework of the two-dimensional Peierls model, for different values of the ratio d/a′, where a′ is the period of the Peierls potential. The distance between the edge and screw components of the partials, as well as their widths, undergo a modulation with period a′, as the dislocation moves, and the amplitudes of such oscillations are shown to depend on d/a′. The stress profile acting on the dislocation complex is analyzed and the effective Peierls stress is estimated for different values of d/a′.