INSITU OBSERVATION OF SUPERDISLOCATION MOTION AND HIGH-TEMPERATURE STRENGTHENING OF NI3AL SINGLE-CRYSTALS

The motion of superdislocations and the development of a deformation structure in a Ni3Al single crystal have been examined by in situ deformation in a high-voltage electron microscope in the temperature range 300-1000 K. It has been revealed that the segments of superdislocations are locked locally because of the cross-slip from {111} to {010}, resulting in the exhaustion of longer mobile dislocations and the creation of immobile screw dislocations. A decrease in the pinning distance of the dislocation thus increases the strength, which is of an athermal nature, at high temperatures.