Orientation dependence of the cyclic deformation behavior and the role of grain boundaries in fatigue damage in copper crystals

In this overview paper, the features and the occurrence of a plateau on the cyclic stress-strain curve in copper single crystals as well as the associated microstructural characteristics are summarized. Unified and comprehensive diagrams are provided. Grain boundaries (GBs) play an important role in fatigue cracking even at intermediate and low-strain amplitudes. However, the associated mechanisms still remain unclear, In the present studies, copper bicrystals. columnar crystals and tricrystals with different orientations were examined. By using the electron channeling contrast (ECC) technique in scanning electron microscopy (SEM), the interaction of persistent slip bands (PSBs) with GBs was clearly revealed. A modified intergranular fatigue cracking mechanism was suggested. The present investigations also disclosed the significant role of the grain boundary triple lines and triple junctions (TJs) in fatigue damage. (C) 2001 Elsevier Science B.V. All rights reserved.