Slip transfer at coherent twin boundaries in Ni3Al and ordered Cu3Au

Slip transfer at coherent twin boundaries in L12-ordered alloys has been investigated by analysis of plastically deformed Cu3Au and Ni3Al specimens in a transmission electron microscope. A comparison between the ex situ deformed material and previous in situ experiments is made. In ordered Cu3Au, antiphase boundaries induced by slip transfer have been found at a coherent twin boundary (CTB), similar to the in situ deformed material. On the other hand, in Ni3Al superlattice intrinsic stacking faults (SISFs) were detected at CTBs which have not been observed in in situ deformed material. A possible mechanism for SISF formation is discussed. The transfer of slip, and the associated creation of stacking faults at CTBs in both materials is described in terms of absorption of superdislocations in the boundary and the general criteria for slip transfer at grain boundaries.