Three intersection mechanisms, involving the glide planes: (11¯1)TB, (001)TB and (11¯5)TB, respectively, were observed - using high-resolution electron microscopy - in type-I twin intersections within the γ-phase. It was found that the intersection mechanism which occurred was related to the thickness of the incident twin. An accommodation mechanism on the (11¯1)TB atomic plane was preferred when the incident twin became very thin. The dislocation dissociations which were involved in (11¯1)TB plane accommodation were the most energetically unfavourable of the dissociations that were involved in the 3 intersection mechanisms. However, the resultant dislocations on the (11¯1)TB planes were the easiest to propagate away from the intersection region. Therefore, (11¯1)TB atomic plane accommodation was considered to be the only mechanism which permitted shear transmission under the influence of the small local stresses provided by the pile-up of incident twinning partials.

Possibility of (11¯1) TB Accommodation Mechanism for Type-I Twin Intersection in γ-TiAl during Room Temperature Deformation. L.C.Zhang, J.G.Wang, G.L.Chen, H.Q.Ye: Philosophical Magazine Letters, 2001, 81[2], 63-70