Macrosegmentation and strain hardening stages in copper single crystals under compression

• We study deformation relief on the surface of monocrystals under compression.
• Macrofragmentation sequence has been determined.
• We found interrelation between segmentation and stages of the stress-strain curve.
• Sample is divided into 5 segments.
• Shear by initially unloaded plane (1¯11) has been observed.

The surface deformation-induced pattern (relief) of copper single crystals with the orientation of the compression axis along [11¯1¯] has been investigated by means of optical, scanning electron and atomic force microscopy. The misorientations between both macroscopic and mesoscopic areas in [11¯1¯]-single crystals have been determined using the electron back scattering diffraction (EBSD) technique. The macroscopic reorientation has been revealed to rotate the crystalline lattice around the [110] axis. The single crystal has been divided into five macrosegments with their misorientations distributed along the compression axis in a manner that the deformation axis sequentially coincided with the crystallographic directions in the order [11¯1¯]-[22¯1¯]-[77¯3¯]-[11¯0]. Shear by unloaded plane (11¯1¯) has been observed. The macrolevel deformation up to 25% has been developing as follows: shear by octahedral planes – development of macrobands – reorientation of the central zones – shear by unloaded octahedral plane in the reoriented zones. The steps of this sequence corresponded to the stages of the stress-strain curves.