Transformation-induced ultra-thin plates of  twins, where the  formed from B2, were studied. It was noted that, whereas such twins were frequently observed in Ti-40Al-10at%V (due to the B2   transformation) they had not been observed in the  lamellae of the 2- lamellar structure which formed via the  and 2  2 +  transformations in TiAl-based alloys or in  which was nucleated from  (A2). The results showed that these ultra-thin twin plates were secondary twins which formed between the advancing fronts of separately nucleated  domains.

G.Shao, P.Tsakiropoulos: Philosophical Magazine A, 1997, 75[3], 657-76