Cyclic deformation behavior of double-slip-oriented copper single crystals III: conjugate double slip orientation on 001–1̄11 side of the stereographic triangle

The cyclic deformation behaviors of [2̄23] and [1̄12] conjugate double-slip-oriented copper single crystals were investigated at constant plastic shear strain amplitude γpl in the range of about 10−4–10−2 at ambient temperature in air. The results of [1̄17] and [001] crystals are included for comparison. Unlike the plot of initial hardening rate θ0.2 against γpl of the [2̄23] crystal which does not exhibit two obvious regions, the plot for the [1̄12] crystal exhibits two regions similar to those in single-slip-oriented crystals. The cyclic stress–strain (CSS) curve of the [1̄12] crystal shows a clear plateau over the range of about 5.0×10−4–4.0×10−3, which is narrower than that of the single slip crystals (6.0×10−5–7.5×10−3) although the saturation shear stress is nearly the same. However, no obvious saturation phenomenon was observed in the cyclically deformed [2̄23] crystals over the range of plastic strain amplitude investigated. Even though the orientations of [1̄12], [1̄17] and [2̄23] crystals are on the same side of the stereographic triangle, their plateau behaviors in the CSS curve are quite different, i.e. the plateau regions of the CSS curves for the crystals located on both sides of the [1̄12] crystal tend to die out except that an obvious plateau region occurs in the cyclically deformed [1̄12] crystals. The results above are mainly attributed to the rather different slip deformation characteristics associated with the different crystal orientations. In addition, two types of deformation bands DBI and DBII, formed in the cyclically deformed [1̄12] and [2̄23] crystals, were also discussed in terms of crystallographic geometry.