DISSOCIATION OF SUPERDISLOCATIONS IN SINGLE-CRYSTAL L10TI-AL-V COMPOUNDS

Single crystals of Ti44Al54V2 (L1(0)) have been deformed to 0.6%-0.8% in uniaxial compression at room temperature, 500, 873 and 1073 K, respectively. The dissociated configurations of superdislocations (b = [011]) in the deformed alloys have been studied under weak beam conditions to determine the temperature dependence of the configurations. The study shows that the dissociated configurations remained co-planar from room temperature to 500 K, but became non-planar at 873 K, in which the superpartial with an antiphase boundary cross-slipped onto a cube plane. In addition to the dissociations in the octahedral and cube planes, superdislocations with a screw character from superkinks whose height increases with increasing deformation temperature. The apparent activation energy for the deformation in the range of 500-1073 K was found to be 0.05 eV. Based on the characteristics of deformation and dislocation structure in this alloy, it is proposed that two different deformation mechanisms operate at the corresponding temperature ranges, i.e. room temperature to 650 K and 650 to 1073 K.