Deformation behavior and interfacial sliding in carbon/copper nanocomposite films deposited by high power DC magnetron sputtering

•Copper-rich carbon/copper nanocomposite films have been obtained by a high-rate DC magnetron sputtering.•Nanoindentation shows the hardness of films to be 2–4 GPa with plasticity approaching that of pure copper.•Interfacial sliding processes are involved in the plastic deformation of films with 90 at.% Cu.

Amorphous carbon–copper nanocomposite films with a carbon content from 7 to 40 at.% have been deposited onto steel, silicon and glass substrates using a high power (> 60 W/cm2) and high-rate DC magnetron sputtering technique. XRD, Raman spectroscopy and TEM results confirm that the deposited films consist of copper nanograins (size < 20 nm) incorporated within the matrix of amorphous carbon (a-C). The structure of films varies from fragmented columnar at the highest copper contents (around 90 at.% Cu) to disordered at increased carbon concentrations. Nanoindentation tests show a reasonable hardness of films (2–4 GPa) with a plasticity approaching that of a pure copper film. The ratio of the plastic work to the total work of the deformation at indentation for copper-rich films (above 90 at.% Cu) reaches up to 86%. The study of surface morphology of the deformation zone around indents in such films reveals localized zones of mutual sliding that indicate to a possible contribution of interfacial effects. The results of the structural and nanoindentation study characterize the a-C/Cu nanocomposite films as possible solid lubricants or as a plastic component for complex tribological coatings.