Ab initio study of 〈1 1 1〉 {1 1 0} superdislocation properties in B2-MgRE (RE = La–Er) intermetallics

The structures and properties of 〈1 1 1〉{1 1 0} superdislocations in B2-MgRE (RE = La–Er) intermetallics are investigated using the Peierls–Nabarro model in combination with generalized stacking fault (GSF) energies. The results demonstrate that the 〈1 1 1〉{1 1 0} superdislocations in B2-MgRE have dissociated into two collinear partials bound to anti-phase boundary. For the same material system, the dislocation dissociated width of screw is narrower than that of edge, while the Peierls energy and stress are larger. With increasing of atomic number, the dislocation dissociated width, Peierls energy and stress in B2-MgRE decrease for both early lanthanides from La to Sm and late lanthanides from Eu to Er. Furthermore, the results of Peierls–Nabarro model show that both stable and unstable GSF energies have important influence on the Peierls energy and stress. With increasing of the ratio of stable GSF energy to unstable GSF energy, the Peierls energy and stress decrease.

• The 〈1 1 1〉{1 1 0} superdislocation in B2-MgRE can dissociate into two collinear partials.
• The dislocation dissociated width of screw is narrower than that of edge.
• The Peierls energy and stress of screw superdislocation is larger than that of edge.
• With increase of the ratio of γAPB/γus, the Peierls energy and stress decrease.
• With increase of atomic number, the Peierls stress in B2-MgRE piecewise decrease.