Positron lifetime studies of the subsurface zones created under dry and lubrication conditions

We present the measurement of the positron lifetime spectra in the subsurface zones in copper samples with surfaces damaged in dry and lubrication conditions. We observe that close to the damaged surface the single vacancies were present, but deeper in the sample treated in the dry condition the vacancy clusters were detected. A zone with dislocations was located deeper than the zone with the vacancies and their clusters.