It was recalled that recent transmission electron microscopic observations had shown that defects which exhibited a contrast that was similar to that expected for antiphase domain boundaries were commonly observed within the  phase of quenched samples of TiAl-based alloys. Detailed examinations were made of several alloys, and it was found that the contrast was complex. It had previously been argued that the complexity was associated both with dynamic interactions and with a supplementary displacement across the antiphase domain boundary. It was shown here that the situation was more complex, and that all of the defects which gave a contrast that was characteristic of antiphase domain boundaries in TiAl-based alloys were really made up of 2 closely-spaced 90 domain boundaries.

X.D.Zhang, M.H.Loretto: Philosophical Magazine A, 1995, 71[2], 421-9