Friction and wear of copper rubbed in the presence of lubricants over a wide range of loads and sliding velocities were studied. The results of friction and wear experiments in the boundary lubrication and elastohydrodynamic lubrication regimes were briefly considered. The structural state of subsurface layers in different lubricant regions was studied by optical, transmission and scanning microscopy analysis. Dislocation density and Burgers vector of individual dislocations in elastohydrodynamic lubrication and boundary lubrication regimes were determined. A laminated structure with thin and elongated grains was formed in the elastohydrodynamic lubrication region. A range of nanocrystalline structures with grain sizes of 20–100nm was formed in the surface layers in the boundary lubrication region. Strong plastic deformation of thin surface layers under friction was accompanied by formation of shear bands in sub-layers of contact spots. Nanohardness at thin surface layers was compared for surfaces rubbed under different lubricant regimes. The hardness of thin surface layers saturates after repeated sliding of Cu and was close to the hardness of nanocrystalline Cu produced by various strong plastic deformation processes.

Dislocation Structure and Hardness of Surface Layers under Friction of Copper in Different Lubricant Conditions. L.Meshi, S.Samuha, S.R.Cohen, A.Laikhtman, A.Moshkovich, V.Perfilyev, I.Lapsker, L.Rapoport: Acta Materialia, 2011, 59[1], 342-8