Intralamellar dislocation networks formed by glide in γ-TiAl I. The mechanism of formation

In a lamellar TiAl alloy deformed at room temperature under an orientation that activates slip parallel to the interfaces, the nphase exhibits intralamellar dislocation networks parallel to the primary slip plane and entirely glissile in their habit plane. Their meshes are mainly rectangular with branches all coplanar, screw or near-screw in character and with Burgers vector of and types. Dislocation organization at and in the near-vicinity of these intralamellar networks suggests a reaction between a family of primary coplanar d011] dislocations that slip in the network habit plane and a family of dislocations that cross-slip from a plane inclined to the lamellae into the network. The reactions result in junctions with Burgers vector that subsequently transform into rectangular units. The presence of these networks is consistent with that of a residual elastic twist between adjacent nlamellae.