DECOMPOSITION OF [011] SUPERLATTICE DISLOCATIONS IN CYCLICALLY DEFORMED TIAL POLYSYNTHETICALLY TWINNED CRYSTALS

Decomposition of [0(1) over bar1$] superlattice dislocations in cyclic ally deformed TiAl polysynthetically twinned crystals has been examine d by focusing on the effect of the Schmid factor (SF) for the operativ e slip systems. The decomposion of the [0(1) over bar1$] superlattice dislocations on (111) into 1/2[1(1) over bar0$] ordinary and 1/2[<(11) over bar 2>] superlattice dislocations occurs more frequently with an Increase in the ratio of the SF for the (111) 1/2 [1(1) over bar0$] sl ip to that for the (111) [0(1) over bar1$]slip. The most effective fac tor in controlling the decomposition is the stress component acting fo r the motion of the resultant 1/2[1(1) over bar0$] dislocations.