Wear behaviour of novel copper alloy as an alternative to copper-beryllium

Copper beryllium age hardenable alloys (Cu-Be) are widely used and appreciated for combining exceptional mechanical and electrical properties. However, the toxicity of these alloys pushes the scientific community to develop alternative alloys. Cu-Ni-Sn alloys are already used in aeronautics and the oil industry to replace Cu-Be when good tribological behaviour is required. Recent studies showed that Cu-Ti alloys, age hardenable, have a higher yield stress and elongation than Cu-Ni-Sn alloys and can approach the mechanical resistance of Cu-Be. In this research work, the wear mechanisms governing the tribological behaviour of a new copper alloy (containing alloying elements such as titanium, nickel or tin) as an alternative to the beryllium containing copper alloys were investigated. Tribological tests under dry conditions were carried out by sliding an alumina ball against three different copper alloys disks applying different loads and during a different number of cycles. Wear volumes were quantified by confocal microscopy while wear morphology and microstructural changes at the surface and subsurface were analysed by SEM and FIB cross-sections. Several wear mechanisms were identified including plastic deformation followed by the build-up of a third body. Friction transitions were measured during sliding as a consequence of the third body formation. The chemical and mechanical properties of the third body were material dependent and determined the wear behaviour of the different copper alloys.