High-resolution electron microscopic images of lamellar γ/a2 interfaces in a TiAl-based alloy were used to show that the interfacial steps had a more diverse range of heights and Burgers vectors than had been reported previously. These observations were not consistent with a Shockley partial dislocation description for the interfacial steps, but instead corresponded to the defects which might be expected on the basis of the topological theory of interfacial defects. The discrepancy between these observations and previous ones was explained in terms of projection effects.

The Character of Steps on Gamma/Alpha-2 Interfaces in Lamellar TiAl-Based Alloys. P.Shang, T.T.Cheng, M.Aindow: Materials Science Forum, 1999, 294-296, 239-42