Defect nucleation from a pre-existing intrinsic I-1 stacking fault in magnesium by molecular dynamics simulations

摘要

In order to clarify defect nucleation in the vicinity of a pre-existing intrinsic I-1 stacking fault (SF) in magnesium (Mg), we carried out molecular dynamics (MD) simulations containing an I-1 SF under several applied shear stresses, using a modified embedded atom method (MEAM) potential. Depending on stress states, different types of defects were generated from the I-1 SF. Under shear stress on {0001} basal plane along < 1 1 (2) over bar 0 > direction, {11 (2) over bar 1} twin was formed from the side ends of the I-1 SF. On the other hand, in the case of higher resolved shear stress (RSS) for < c+a > pyramidal slips, < c+a > partial dislocations were generated with SFs on the first-pyramidal planes as well as the second-pyramidal planes. The dissociation reactions of the dislocations at the side ends of the I-1 SF were energetically evaluated, and it was implied that nucleation of the < c+a > dislocations on the first-pyramidal planes is more favorable than on the second-pyramidal planes. These results suggest that I-1 SFs are attractive defects for nucleation of < c+a > dislocations.