A back-force model was proposed for simulating dislocation-cutting of a γ′ precipitate from the point of view of the work involved in making or removing an antiphase boundary. The first dislocation, or a leading partial of a super-dislocation, was acted upon by a back-force whose magnitude was equal to the antiphase boundary energy. The second dislocation, or the trailing partial of a super-dislocation, was attracted by the antiphase boundary with a force of the same magnitude. The model was applied using a 3-dimensional discrete dislocation dynamics code, and demonstrated that a super-dislocation nucleated when 2 dislocations piled up at the interface. The width of dislocations was naturally balanced by the antiphase boundary energy and the repulsion of dislocations. The antiphase boundary energy adopted was calculated, by ab initio analysis, on the basis of density functional theory. These discrete dislocation dynamics simulations were then applied to more complicated cases, such as dislocations near to the edges of a cuboidal precipitate and those at a γ/γ′ interface covered by an interfacial dislocation network. The former simulation showed that dislocations penetrated into a γ′ precipitate as a super-dislocation from the edge of the cube, when running around the cube to form Orowan loops. The latter revealed that dislocations became wavy at the interface due to the stress field of the dislocation network, then cut into the γ′ precipitate through the interspace of the network. The present model could be used to study the dependence of the cutting resistance upon the spacing of dislocations in the interfacial dislocation network.

Discrete Dislocation Dynamics Simulation of Cutting of γ’ Precipitate and Interfacial Dislocation Network in Ni-Based Superalloys. K.Yashiro, F.Kurose, Y.Nakashima, K.Kubo, Y.Tomita, H.M.Zbib: International Journal of Plasticity, 2006, 22[4], 713-23