Static dislocation interactions in thin channels between cuboidal particles

A discrete dislocation model (DDM) is used to rationalize the stability of interface dislocation configurations in particle strengthened alloys with microstructures like those found in single crystal superalloys, where large cubes of ordered γ′-phase (1 μm) are separated by thin γ-channels (0.1 μm). The model combines three elements which contribute to the overall stress state: (i) external constant applied stress, (ii) coherency stresses (due to a misfit between matrix and particle) and (iii) stresses associated with dislocations. Peach–Koehler forces on interface dislocations are calculated based on this overall stress state. The calculations are performed using a 2D model for a 〈1 1 0〉-projection of the overall microstructural scenario. The stability of simple dislocation arrays at the γ/γ′-interface is studied considering the interaction of two octahedral slip systems in the thin γ-channels. As compared to the case where only one octahedral slip system is activated, the simultaneous glide in two octahedral slip systems further decreases the number of dislocation loops which can enter the γ-channel in each of the two slip systems.