EXTENDED DISLOCATIONS AND DISLOCATION DIPOLES IN PLASTICALLY DEFORMEDSIC SINGLE-CRYSTALS

SiC single crystal plates are deformed in bending at 1700 and 1750-deg rees-C in air. Smoothly curved extended dislocations of total (a/3) [1 12BAR0] Burgers vectors are formed, many of which are arranged in grou ps of parallel dislocations on basal planes. The slip planes of differ ent groups have mostly distances smaller than 100 nm. The stacking fau lt energy of about 1.7 mJ/m2 is estimated from the width of the dissoc iated dislocations. Frequently, dipoles of extended dislocations havin g much lower width form, which agrees with calculations of their equil ibrium configurations. The shape of dislocations crossing each other o n parallel planes depends on the sequence of the partial dislocations and can be understood by the mutual elastic interactions of the latter . It is argued that long-range elastic dislocation interactions essent ially contribute to the flow stress at these high temperatures.