Dry sliding tribological properties of nanostructured copper subjected to dynamic plastic deformation

Dynamic plastic deformation (DPD) technique was used to synthesize a bulk nanostructured Cu sample with nano-scale twin bundles (about 1/3 in volume) embedded in nano-sized grains. Dry sliding friction and wear tests of ball-on-plate contact configuration were carried out for the DPD and the coarse grained (CG) Cu samples. The longitudinal-sectional observations of wear track were performed to character the subsurface microstructure of two kinds of Cu samples. Experimental results show that the DPD Cu exhibits an enhanced wear resistance relative to that of the CG Cu under a certain sliding condition. There is an obvious difference in subsurface microstructural evolution between the DPD and CG Cu during wear process. For the CG Cu, plastic deformation induced grain refinement plays an important role, and dynamic recrystallization follows after a large plastic deformation accumulation. However, for the DPD Cu sample, dynamic recrystallization can be observed in the initial sliding and subsequent plastic deformation generates gradually.