A back-force model was proposed for simulating dislocations cutting into a γ′ precipitate. 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 a trailing partial of a super-dislocation, was attracted by the antiphase boundary with a force of the same magnitude. The model was encoded in a 3D discrete dislocation dynamics code and it was demonstrated that a super-dislocation nucleated after 2 dislocations piled up at the interface, and that the width of dislocations was naturally balanced by the antiphase boundary energy and the repulsion of dislocations. The antiphase boundary energy adopted here was calculated by ab initio analysis, on the basis of density functional theory. The 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, and then cut into the γ′ precipitate through the interspace of the network. The model proposed here could be applied to studies of 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