Antiphase domain boundaries and their importance for dislocation behaviour in Ni3Al based alloys

摘要

The antiphase domain boundary structures within several rapidly-solidified alloys based on Ni3Al have been examined both in the as-quenched state and after heat treatments. The domain boundary energy shows a mild anisotropy, as deduced from the shape of the domains. The degree of anisotropy increases with the equivalent aluminium content of the alloy. Slightly deformed materials contain superdislocation pairs whenever domain boundaries are absent and single dislocations wherever domain boundaries occur. The superdislocations lie predominantly on {100} planes where glide can also take place. Superdislocations dissociate into two separate single dislocations on meeting a domain boundary, leading to significant strengthening and improvement of ductility.