Dissociated core configurations of [1̄01] superdislocations and their relative stability in single crystal Ti-56Al deformed at 573 K

Abstract

The core configurations of [1̄01] superdislocations in single crystal Ti-56Al have been investigated by high resolution electron microscopy. The results show that the dissociated superpartial dislocations in deformed Ti-56Al at 573 K adapt two different configurations: (1) coplanar dissociation; and (2) rooftop type dissociation in which each coupling superpartial (12[1̄01]) lies in two different {111} slip planes. The rooftop configuration appears to be formed by a thermally activated process and provides the pinning of gliding superdislocations at this temperature. The calculated elastic interaction energy between the coupling superpartial dislocations in the anisotropic medium shows that the rooftop configuration has lower interaction energy than that of the coplanar configuration. Based the observation and theoretical calculations, a model based on partial cross slip and its reversal is proposed for the anomalous hardening in the range of RT-650 K.