Dissociation of pyramidal slip in deformation of single crystal magnesium

Pyramidal slip in magnesium and other hexagonal close-packed (hcp) metals is important in accommodating strain along the c-axis, yet the mechanism for pyramidal slip in Mg remains unclear and controversial. In this work, we use four interatomic potentials for Mg developed by different research groups, i.e. two EAMs and two MEAMs, and simulate pyramidal slip under c-axis tension or compression. Burgers vector analyses show that, irrespective of the potentials and the loading direction, the pyramidal slips in single crystal Mg are on {101 ̅1}, and {112 ̅2}. However, (112 ̅2) pyramidal II dislocations are only observed by some potentials. All four potentials generate the same pyramidal I dissociation: a leading partial with a Burgers vector of 1/2∙1/2[011 ̅2], and a trailing partial with a Burgers vector of 1/2∙1/2 [011 ̅2]+1/2∙1/3[21 ̅1 ̅0], with a stacking fault between the partials. In addition, <c+a> dislocation could dissociate into two ½<c+a> partials with a burgers vector of 1/6[112 ̅3] on (112 ̅2) plane. Depending on the potentials, the core structure of the trailing partial is different.