Nanocrystallization and Texture Transformation in the Surface Layer of Copper Induced by Surface Mechanical Attrition

A nanostructured surface layer was synthesized in a pure copper plate by means of surface mechanical attrition (SMA). The evolutions of microstructure and orientation were examined by using XRD, TEM and ODF. The microstructural evolution with the treatment time can be divided into two stages: the first is characterized by a formation of nc grains with small to medium misorientations in the surface layer and a texture transformation from rolling type to shear one in the near-surface layer, and the second by a significant increment of misorientations between the nc grains and a texture transformation from shear type back to rolling one. It might be reasonably deduced that shear stress can effectively induce grain refinement, and the combination of shear and compress stresses might be helpful for the increment of grain boundary misorientations.