It was recalled that, when body-centered cubic crystals underwent plastic deformation, the operating slip planes were often non-crystallographic. It was shown here, by performing atomistic simulations of the activation pathway of dislocation jumps in body-centered cubic Fe, that the main reason for such crystals to exhibit this phenomenon was that one type of kink pair had a significantly lower energy than those of all of the other types on the same slip plane. Dislocation motion therefore could not continue on the same slip plane, and the dislocation had to cross-slip onto an intersecting slip plane after each atomic jump. In the long run, the average slip plane was therefore expected to be zig-zag and non-crystallographic.

Dislocation Kink-Pair Energetics and Pencil Glide in Body-Centered-Cubic Crystals. A.H.W.Ngan, M.Wen: Physical Review Letters, 2001, 87[7], 075505 (3pp)