Molecular statics methods were used to simulate dislocations in L10 structures. Three different embedded-atom method potentials were fitted to the bulk properties of -TiAl. The 3 potentials were fitted so as to produce complex stacking-fault energies of 120, 320 or 580mJ/m2. Core structures were determined, using each of the potentials, for screw, 30 mixed, 60 mixed and edge dislocations. The cores were all planar, except for the screw orientations which had been calculated by using the 320 and 580mJ/m2 potentials. These exhibited appreciable amounts of non-planar spreading. The 60 orientations for these 2 potentials exhibited a tendency for the screw component of the displacement to spread out of the plane and for the edge component to spread on the glide plane. The screw orientation, for the 320mJ/m2 potential, was found to have 2 possible states: planar and non-planar. Friction stresses were estimated for all orientations of the 320mJ/m2 potential; since this one appeared to represent -TiAl most closely. The friction stresses for the other potentials were determined only for those orientations which produced the highest friction stress for the 320mJ/m2 potential. Moreover, the close-packed directions, screw and 60, exhibited the highest friction stress. Less closely-packed directions had considerably lower values. The friction stress for the 320mJ/m2 potential was predicted to be 250MPa. This value was in good agreement with experimental data on the critical resolved shear stress of -TiAl. Previously predicted effects of ordering upon the friction stress were observed. These variations had a considerably smaller effect than did the atomic density along the orientation line.

Atomistics Simulations of Structures and Properties of ½<110> Dislocations using Three Different Embedded-Atom Method Potentials Fit to γ-TiAl. J.P.Simmons, S.L.Rao, D.M.Dimiduk: Philosophical Magazine A, 1997, 75[5], 1299-328