Deformation under single slip of ordinary dislocations in single crystal Ti–56Al

Single crystals of γ-Ti–56Al were deformed in three different compression orientations: [3̄ 12 7], [1̄63], [1̄ 12 5]. The yield stress and the critical resolve shear stress (CRSS) under single slip of ordinary dislocations between 673 and 1073 K not only exhibit anomalous hardening, but also depend on deformation orientations in single crystal γ-Ti–56Al. Each yield stress curve exhibits positive temperature dependence with a maximum value near 1073 K. The CRSS value of each curve for a given temperature was correlated with the Schmid factor ratio between the octahedral cross slip plane and the primary slip plane. The deformed specimens from various orientations and temperatures have been investigated by TEM using two beam and weak beam techniques. The morphology of ordinary dislocations does not change significantly from room temperature to 1073 K. The dissociation of ordinary dislocations was observed under weak beam in the specimen deformed at 873 K.