Subject classification: 61.72.Ff; 62.20.Mk; S1.3The dislocation structures of cyclically deformed coplanar ½ 2 255 and ½ 2 233 double-slip-oriented copper single crystals were studied by transmission electron microscopy and related to the macroscopic mechanical behavior. Experimental results indicated that the crystallographic orientation has nearly no effect on the cyclic stress-strain (CSS) behavior and dislocation structures of both ½ 2 255 and ½ 2 233 coplanar double-slip-oriented Cu single crystals. The cyclic dislocation structure of coplanar double-slip crystals consists primarily of dislocation cells, the scale of which decreases with increasing applied strain amplitude. Under certain applied strain amplitudes, the observed dislocation cells exhibit different features, including dislocation wall-like and persistent slip band (PSB) ladder-like features, which are favourable for accommodating much more plastic strains during cyclic deformation. The occurrence of a quasi-plateau, where the stresses show a slow increase with plastic strain amplitude, in the CSS curve of coplanar double-slip-oriented Cu single crystals was believed to result from the joint effects of the scale change of the cell structure and the formation of PSB ladder-like cell structure.

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