SEM Electron Channeling Contrast Imaging of Dislocation Structures in Fatigued [017] Cu Single Crystals Oriented for Critical Double Slip

Dislocation structures in fatigued (017) critical double-slip-oriented Cu single crystals were studied using the electron channeling contrast technique in scanning electron microscopy. It was found that the dislocation structures are strongly dependent upon the applied plastic strain amplitudepl .A spl falls into the quasi-plateau region in the cyclic stress-strain curve of the (017) crystal, a special ''two-phase'' dislocation structure, i.e., persistent slip band ladder-like structures and matrix labyrinth structures, was observed. Whenpl � 3:0 � 10 � 3 , which is beyond the quasi-plateau region, two types of deformation bands denoted DBI and DBII were observed. The dislocation microstructures in DBI and DBII consist mainly of well-developed regular labyrinth structures and densely-aligned dislocation walls, respectively, and the microstructures at the intersection region of DBI and DBII comprise dislocation walls together with a number of dislocation cells. The orientation dependence of microstructures in DBI and DBII is further summarized and discussed. (doi:10.2320/matertrans.M2009439)