Properties of ⟨110]{111} slip in Al-rich γ-TiAl deformed at room temperature -: I.: Transmission electron microscopy analysis of deformation debris

Dislocation micromechanisms operating in an Al-rich gamma-TiAl single crystal deformed by 1/2 h (110]{111} slip are investigated with particular attention paid to the generation and to the organization of prismatic loops and to the reactions of these with mobile dislocations. Loops are frequently arranged as staircase strings with one loop extremity aligned in the screw direction with the extremity of a nearby loop. Strings and dislocations tend to aggregate into loose walls. Also typical of deformation at room temperature are elongated loops piled up into multipoles whose extremities are often aligned with the screw direction. The causes of dislocation point- and hairpin-like pinning are discussed in the context of pre-existing models.