Wear resistance and electroconductivity in copper processed by severe plastic deformation

The wear properties and electroconductivity of three ultra-fine grained (UFG) commercially pure copper materials, subjected to combinations of high-pressure torsion (HPT) and equal-channel angular pressing (ECAP), were studied and compared with conventional coarse-grained (CG) copper. The results are discussed as a function of microstructure and microtexture. The UFG specimens demonstrate no significant decrease in electroconductivity by comparison with CG copper. The conductivity of an ECAP+HPT specimen showed a value of 99.3% of annealed copper and the same sample showed the lowest wear rate among the UFG specimens. However, all UFG specimens gave higher wear rates than CG copper and there was no evidence for the enhanced wear resistance reported for nanocrystalline copper obtained by surface mechanical attrition treatment (SMAT) and electrodeposition. This result is discussed in the context of two competing processes: shear by sliding and normal compression by impact load.