The core structures of <100>, <110> and <111> dislocations were studied by means of molecular static calculations, using an embedded atom potential. The response of dislocation cores to applied homogeneous shear stresses was investigated, and the Peierls stresses of straight dislocations with edge, screw or mixed nature were determined. The results were compared with previous calculations which had involved the use of different potentials. A simple line tension model was applied to the transition from <111> to <110> glide in so-called hard-oriented monocrystals. The <100>{011} slip system, which was the most frequently observed, was reproduced by the calculations, and even the core structure was almost identical for all of the potentials which had been used. The use of a particular potential could also lead to a prediction of the low mobility of <110> dislocations, and their tendency to decompose into two <100> dislocations. Clear differences in the effect of the potentials could be seen in the case of the <111> screw dislocation. The dislocation core in the present simulations was highly non-planar, and therefore sessile. As in many body-centered cubic metals, the <111> screw dislocation seemed to impair plasticity in the so-called hard orientation. The results for <111> dislocations were in excellent agreement with experimental observations.

Core Properties and Motion of Dislocations in NiAl R.Schroll, V.Vitek, P.Gumbsch: Acta Materialia, 1998, 46[3], 903-18