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 m icrostructures like those found in sin,ale crystal superalloys, where large cubes of ordered gamma ' -phase (1 mum) are separated by thin gamma -chann els (0.1 mum). The model combines three elements which contribute to the ov erall stress state: (i) external constant applied stress, (ii) coherency st resses (due to a misfit between matrix and particle) and (iii) stresses ass ociated with dislocations. Peach-Koehler forces on interface dislocations a re calculated based on this overall stress state. The calculations are perf ormed using a 2D model for a [110]-projection of the overall microstructura l scenario. The stability of simple dislocation arrays at the gamma/gamma ' -interface is studied considering the interaction of two octahedral slip s ystems in the thin gamma -channels. As compared to the case where only one octahedral slip system is activated, the simultaneous glide in two octahedr al slip systems further decreases the number of dislocation loops which can enter the gamma -channel in each of the two slip systems. (C) 2001 Elsevie r Science B.V. All rights reserved.