Slip planes in bcc transition metals

Slip in face centred cubic (fcc) metals is well documented to occur on {111} planes in < 110 > directions. In body centred cubic (bcc) metals, the slip direction is also well established to be < 111 >, but it is much less clear as to the slip planes on which dislocations move. Since plasticity in metals is governed by the collective motion and interaction of dislocations, the nature of the relevant slip planes is of critical importance in understanding and modelling plasticity in bcc metals. This review attempts to address two fundamental questions regarding the slip planes in bcc metals. First, on what planes can slip, and thus crystallographic rotation, be observed to occur, i.e. what are the effective slip planes? Second, on what planes do kinks form along the dislocation lines, i.e. what are the fundamental slip planes? We review the available literature on direct and indirect characterisation of slip planes from experiments, and simulations using atomistic models. Given the technological importance of bcc transition metals, this review focuses specifically on those materials.