First-principles study of the dislocation core structures on basal plane in magnesium

The core properties of dislocations on (0001) basal plane in pure magnesium, including screw, 30 degrees, 60 degrees and edge dislocations, have been studied by combining the generalized stacking fault energies from first-principles calculation with the improved 2D Peierls-Nabarro model. The calculated results showed that all full dislocations have dissociated into two partial dislocations. With increasing the angle between the dislocation line and Burgers vector, the distance between the two partial dislocations is increased. Then the dislocation line energy surfaces E-T as a functional of shift displacement t of dislocation center and separation distance d between the partials are calculated, several stable configurations with local minimum energy have been found for screw and 60 degrees dislocations, while only one stable configuration is formed in 30 degrees and edge dislocations. Finally, the Peierls energies and Peierls stresses along the reaction path have been determined. The calculated Peierls energies for screw and 60 degrees dislocation lines along direction [1 (2) over bar 10] are energetically larger than 30 degrees and edge dislocation lines along [10 (1) over bar0]. The obtained Peierls stresses are in agreement with experimental values and other theoretical calculations. (C) 2013 Published by Elsevier Masson SAS.