HRTEM investigation of dislocation interactions in WC

The defect structure of the carbide phase in WC-Co alloys is studied by high resolution transmission electron microscopy. 1/3 <1-213> dislocations dissociated into 1/6 <1-213> partial dislocations in the {10-10} prismatic plane are studied and the atomic structure of the associated stacking fault is characterized. Another type of prismatic fault bounded by 1/2 <10-11> partial dislocations is also analysed. Interactions of extended dislocations are often observed and lead to the formation of dipoles when the dissociation occurs in parallel prismatic planes, or to 1/6 <11-20> stair-rod dislocations when the dissociation takes place in intersecting prismatic planes. The reaction of 1/6 <1-213> partial dislocations leads to sessile defects that are expected to limit the plasticity of the WC phase even at high temperature.