The nature of the intrinsic stacking faults on {001} planes in this A15 intermetallic compound was investigated by using energy-dispersive X-ray spectroscopy in a field-emission transmission electron microscope. Line scans were made across edge-on faults, using an electron beam with an approximate diameter of 0.5nm. It was found that the Al concentration was enhanced at the fault. Together with previously obtained crystallographic data, this implied that an {004} layer composed only of Nb atoms was removed in order to form these intrinsic stacking faults. The configuration of the faults implied that they could form via Nb-vacancy coalescence, and could act as nuclei for the precipitation of the D8b compound, Nb2Al.

Identifying the Character of Intrinsic Stacking Faults in the A15 Compound Nb3Al. T.S.Rong, L.S.Smith, M.Aindow, I.P.Jones, M.H.Loretto: Philosophical Magazine Letters, 2000, 80[8], 519-24