Kinks on an a/2<111> screw dislocation in the body-centered cubic material were studied in detail by atomistic computer simulation, using quantum-based multi-ion interatomic potentials derived from model generalized pseudopotential theory, together with a Green’s function simulation technique. The stable core structure of the rigid screw dislocation was predicted to be weakly polarized and to spread out on three {110} planes in <112> directions; with 2 energetically equivalent configurations. This double degeneracy led to the possibility of antiphase defects forming on the dislocation line as well as multiple kinks and kink pairs. The zero-stress formation energies of 16 possible kink-pair configurations were calculated for the body-centered cubic Ta, and the values ranged from 0.67 to 1.84eV. The lowest kink-pair energy of the perfect screw was in good agreement with the best empirical estimate. Under an applied stress, the corresponding kink–kink interaction energy exhibited a λ-1 elastic attraction when the separation, λ, was greater than 7b = 20Å. The stress required to maintain the kink pair varied as λ-1.5.

Kink-Pair Mechanisms for a/2<111> Screw Dislocation Motion in BCC Tantalum. L.H.Yang, J.A.Moriarty: Materials Science and Engineering A, 2001, 319-321, 124-9