Cyclic deformation behavior of double-slip-oriented copper single crystals I: coplanar double slip orientation on 011-1̄11 side of the stereographic triangle

Abstract

The cyclic deformation behaviors of [2̄33] coplanar double-slip-oriented and [4̄ 18 41] single-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. It was revealed that the cyclic deformation behavior of copper single crystal oriented on the 011-1̄11 side is distinctly dissimilar from that on the 001-1̄11 and 001-011 sides in the stereographic triangle. The plot of initial hardening rate θ0.2 against γpl of [2̄33] crystal exhibits two regions as presented for single-slip-oriented crystals. The critical strain amplitude (≈3.5×10−3), corresponding to the occurrence of the secondary hardening stage in the cyclic hardening curve of the [2̄33] crystal, was found to be an intermediate value between that for single-slip-oriented single crystals and polycrystals. The result shows that the cyclic hardening behavior of the [2̄33] crystal, as compared with that of single-slip-oriented crystals, is more close to that of polycrystals. Instead of a clear plateau, the cyclic stress–strain (CSS) curves of the [2̄33] crystals shows a quasi-plateau over the range of about 3.0×10−4–2.0×10−3, which would be greatly attributed to the mode of dislocation interactions between slip systems operating in the crystal. The habit plane of two types of deformation bands DBI and DBII, formed in the cyclically deformed [2̄33] crystal, are perpendicular to each other strictly, and they develop with increasing applied strain amplitude.