SEM and SPM investigations of the surface of antifriction aluminium alloys of the system Al-5%Si-4%Cu-6%Sn

Two antifriction alloys based on the Al–5%Si–4%Cu–4%Sn system with the addition of bismuth, lead, and cadmium were investigated. The effect of these elements on the change in surface topography and the tribological properties of the samples was studied. Tribological tests simulating the work of the friction unit were carried out using "shoe-roller" scheme. After heat treatment in both alloys, the phase components acquired a globular shape. Mass transfer between the shoe and the roller led to the formation of a film of secondary structures of variable thickness on the roller surface. SEM and EBSD allowed observing a near-surface layer (50-100 μm thick) with a modified structure and grain shape. SPM made it possible to evaluate the difference in the mechanical properties of the surface layer at the nanoscale level. It was shown that the material was strengthened in the process of friction. (paper)