The influence of antiphase boundaries on the kinetic process of the L12 → D022 structural change in an Ni3Al0.45V0.50 alloy was investigated by transmission electron microscopy. The structural change included two kinetic factors, i.e., the periodic introduction of antiphase-shifted planes in the L12 structure and V diffusion in the L12 matrix. The results revealed that antiphase boundary migration was accompanied by V diffusion as if to sweep the V atoms out of the antiphase domains. It was also found that the antiphase boundaries served as the nucleation sites of the D022 regions, because the combination of the migrated antiphase boundaries produced the antiphase-shifted planes in the L12 structure. On this basis, it was proposed that the antiphase boundaries brought together the two kinetic factors in the process of the L12 → D022 structural change, the physical origin of which was the variation in the charge density distribution of the antiphase domains due to antiphase boundary migration.

The Role of Antiphase Boundaries in the Kinetic Process of the L12→D022 Structural Change of an Ni3Al0.45V0.50 Alloy. M.Tanimura, Y.Koyama: Acta Materialia, 2006, 54[16], 4385-91