High-resolution electron microscopy of the Σ = 5 [001] (310) grain boundary in NiAl

Abstract The structure of a highly oriented NiAl Σ = 5 [001] (310) grain boundary has been imaged by high-resolution electron microscopy and analysed by multislice image calculations. This grain boundary exhibits an asymmetry produced by a rigid body displacement of approximately 1/2d 1 30 along the grain boundary, but does not show any measurable expansion of the grain boundary. The match between the simulated and experimental images of this grain boundary is improved by changing the stoichiometry of the boundary, which can be accomplished by adding antisite defects and vacancies. The final model structure incorporates 50% constitutional vacancies on the nickel sites adjacent to the boundary plane and a replacement of the aluminium sites adjacent to the boundary plane with 50% nickel antisite defects and 50% vacancies.