Formation of thick nanocrystalline surface layer on copper during oscillating sliding

Severe plastic deformation on the subsurface layer of metals by means of sliding under loading could lead to the formation of nanocrystalline surface tribolayer. In this work, a nanocrystalline surface layer with a thickness of 120 mu m is formed on a coarse-grained pure copper sheet after oscillating sliding at room temperature in argon. In the as-formed top surface layer, the average transverse and longitudinal grain size is about 20 nm and 37 nm, respectively. This work provides experimental evidence that dry sliding friction can be developed as a surface nanocrystallization technology to produce nanocrystalline surface layer with a thickness exceeding 100 mu m. (C) 2011 Elsevier B.V. All rights reserved.