Super-dislocation core structures in L12 Ni3Ge, Fe3Ge and Ni3Al were determined on the basis of ab initio generalized stacking fault energetics calculations. Super-dislocation dissociation schemes, partials separation and core widths were calculated within the modified Peierls-Nabarro model with ab initio generalized stacking fault parameterization. Calculated super-dislocation core structure parameters were found to be in agreement with available experimental data. A super-dislocation core with type-I (fourfold) dissociation was found to be unstable in Fe3Ge but stable, and energetically preferred, in Ni3Ge and Ni3Al. These results suggested a mechanism for octahedral glide being inactive in Fe3Ge.

Superdislocation Core Structure in L12 Ni3Al, Ni3Ge and Fe3Ge: Peierls-Nabarro Analysis Starting from ab initio GSF Energetics Calculations. Mryasov, O.N., Gornostyrev, Y.N., Van Schilfgaarde, M., Freeman, A.J.: Acta Materialia, 2002, 50[18], 4545-54