Effect of orientations on cyclic deformation behavior of Ag and Cu single crystals: Cyclic stress–strain curve and slip morphology

This work investigates the differences in the cyclic stress-strain (CSS) curves and surface slip morphologies of the fatigued Ag and Cu single crystals with different orientations. It is found that the average saturation resolved shear stress tau(s) of Ag single crystal is similar to 6 MPa less than that of Cu single crystal with the same orientation. In addition, for the same kind of crystal, whether Cu. or Ag, it seems that the saturation shear stress of coplanar double-slip-oriented single crystal is slightly higher than that of single-slip-oriented single crystal. In addition, the surface deformation morphologies (deformation bands and slip bands) are strongly dependent on the crystallographic orientations. As the crystallographic orientations of the crystals deviate from the best observation orientation [1 (2) over bar1] zone, on the one hand, the resolved shear stress tau(s) rises and some braid slip bands (SB) appear on the crystal surface, and, on the other hand, the interacting angle between the primary slip bands and the deformation band II (DBII) changes from perpendicular to a gradually smaller angle. Based on the experimental results, the relationships between crystallographic orientation, CSS curves and slip morphologies (including DBII and SB) in the fatigued Ag and Cu single crystals are discussed. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.