材料期刊网

Three intersection mechanisms with the gliding planes (11(1) over bar)(TB), (001)(TB) and (11(5) over bar)(TB) respectively have been observed by high-resolution electron microscopy in, the type-I twin intersection of gamma -TiAl. It was found that the intersection mechanism that occurred was related to the thickness of the incident twin. The accommodation mechanism on the (11(1) over bar)(TB) atomic;plane is preferred when the incident twin becomes very thin. The dislocation dissociations of the (11(1) over bar)(TB) plane accommodation are the most energetically unfavourable of the dissociations of the three intersection mechanisms; however, the resultant dislocations on the (11(1) over bar)(TB) planes are the easiest to propagate away from the intersection area. Accordingly, (11(1) over bar)(TB) atomic plane accommodation is considered to be the only mechanism allowing shear transmission under the small local stress of the pile-up of the incident twinning partials.