Dissociated dislocations in Ni: a computational study

A systematic computational study of the behavior of a ( 1 / 2 ) 〈 1 1 0 〉 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 ′ .