Experimental observations of subsurface damage and oxidative wear in Al-based metal–matrix composites

The dry sliding wear of three Al-based metal–matrix composites containing a high amount of reinforcement (up to 65 vol.%) sliding against a steel counterface was found to be dominated by an oxidation mechanism. Wear, in fact, is given by the fragmentation of an oxidized scale, which forms during sliding. Although the wear mechanism is the same, the three materials display very different wear rates. This was found to be connected with the different roles of subsurface plastic deformation. The interplay between the subsurface plastic deformation and the microstructure of the composites is thus experimentally investigated and its influence on the stability of the surface scale clarified.