Secondary slip of screw dislocations in zirconium

Plasticity in hexagonal close-packed zirconium is controlled by screw dislocations which easily glide the prismatic planes where they are dissociated. At high enough temperatures, these can deviate out of prism to also first order pyramidal and basal planes. To get a better understanding secondary slip systems, we have performed molecular dynamics (MD) simulations dislocation gliding plane. The remains dissociated plane it performs random motion occasionally cross-slips its habit nucleation propagation kink-pair. Deviation always pyramidal, with an equal probability cross-slip two on both sides plane, thus leading average. Basal appears therefore as combination stress regime explored MD simulations. This confirmed nudged elastic band (NEB) calculations. But NEB calculations reveal change mechanism for decreasing applied stress. low stress, kinks do not lie anymore They now spread planes, fully compatible confined seen experiments. slip, competition favoured at pure zirconium.