Effect of counterface materials on dynamic recrystallized structure and wear resistance of nanostructured Cu

Bulk nanostructured Cu sample with nano-scale twin bundles embedded in nano-sized grains was synthesized by using dynamic plastic deformation (DPD) technique. Dry sliding tribological properties of the DPD and the coarse grained (CG) Cu samples were investigated when sliding against different counterfaces. There is an obvious difference in the relative wear resistance of the DPD to the CG Cu as a result of the change of the counterface materials. Either for the DPD Cu or the CG Cu sample, the wear rate was much larger when sliding against Cu ball than that when sliding against WC-Co or AISI 52100 steel ball. The DPD Cu sample shows almost same wear rate compared with the CG Cu sliding against Cu or AISI 52100 steel ball, which is quite different from the enhanced wear resistance for the DPD Cu sample sliding against WC-Co ball. The worn subsurface structure for two kinds of Cu samples sliding against different counterfaces, was constituted by heavily deformed nanostructured mixing layer (NML) and ultra-fine grained dynamic recrystallization (DRX) layer. Structure characteristics of the NML and DRX layer determines wear rates of the Cu samples. When sliding against Cu or AISI 52100 steel ball, there are heavily cracked NMLs and extremely fine DRX grains in the subsurface, comparing with that sliding against WC-Co ball. This structure feature leads to quick spread of cracking and high flaking rate of the NML, which corresponds to much higher wear rate for both Cu samples.