Towards resolving the anonymity of pyramidal slip in magnesium

Plasticity in magnesium crystals oriented for c-axis compression has been usually attributed to < c+a > dislocation slip on second-order pyramidal {11 (2) over bar2} planes. Through molecular dynamics simulations, we investigated the formation and slip characteristics of < c+a > dislocations on second-order pyramidal planes. It is shown that the critical c-axis compressive stress for these dislocations is almost seven times that for < c+a > dislocations on first-order pyramidal {10 (1) over bar1} planes. In particular, it is concluded that first-order pyramidal near-screw < c+a > dislocations play a predominant role during the c-axis compression of magnesium crystals. Careful reexaminations of published experimental observations show good agreements with the current predictions. (C) 2015 Elsevier B.V. All rights reserved.