DISLOCATION TRANSFORMATIONS AND THE ANOMALIES OF DEFORMATION CHARACTERISTICS IN TIAL .1. MODELS OF DISLOCATION BLOCKING

An analysis is given of the models proposed to explain the temperature peak of yield point in TiAl. Results are provided of a theoretical investigation into the glissile dislocations of different types and of transmission electron microscopy (TEM) observations of nodes formed by these dislocations. Consideration is given to mechanisms of superdislocation blocking due to their resplitting into noncoplanar configurations such as "roof"-type barriers, barriers of the two-layer twin type, barriers similar to Kear-Wilsdorf locks and Lomer-Cottrell-Hirth barriers. A new blocking mechanism related to trapping of single dislocations in deep Peierls valleys is proposed.