Cyclic deformation behavior of double-slip-oriented copper single crystals IV: change of hysteresis loop shape and formation of persistent slip bands

Abstract

Abstract The changes of hysteresis loop shape parameter V H with number of cycles N in copper single crystals oriented for conjugate, critical and coplanar double slip were detected systematically during cyclic deformation. The results of multiple slip-oriented copper single crystals [001], [111] and [011] were also included for summary. It was shown that, unlike the result obtained for single slip crystals, the crystallographic orientation has a strong effect on the trend of hysteresis loop shape change during cycling for double slip-oriented crystals. The persistent slip bands (PSBs) may occur at certain strain amplitudes within or even below the plateau region in the cyclic stress–strain (CSS) curve for [112] crystals, while it is very hard for PSBs to form in [233] and [017] crystals. In brief, whether V H could be adopted to determine the PSB nucleation stress is closely related to the existence or non-existence of a plateau or quasi-plateau region in the CSS curves of the crystals with various orientations. The PSB nucleation stresses determined by the parameter V H for copper single crystals with different types of double slip orientations were compared and discussed.