Dislocation structures for octahedral slip in Ni₃(Si, Ti) single crystals at elevated temperatures

Abstract

The dislocation structures in L1₂-type Ni₃(Si, Ti) single crystals, which deform by the [101](111) octahedral slip system at high temperatures, were observed as a function of temperature by means of the weak-beam transmission electron microscopy (TEM) method combined with a tilting technique. The dislocation structure had a tendency to form the looped configuration and their edge components became more significant with increasing temperature. It was shown that the dislocation segment with the screw component dissociated exclusively in the (010) plane while the dislocation segment with the edge component climbdissociated in the (101) plane perpendicular to the (111) plane. It was demonstrated on the basis of the present TEM observation that high-temperature deformation by the (111) slip system in Ni₃(Si, Ti) single crystals is controlled by non-conservative motion of the [101] edge dislocations connected with the antiphase boundary.