SPECIAL ISSUE PAPER Wear of metals: a consequence of stable/unstable material

Abstract: Wear of metals in dry sliding is dictated by the material response to traction. This is demonstrated by considering the wear of aluminium and titanium alloys. In a regime of stable homogeneous deformation the material approaching the surface from the bulk passes through microprocessing zones of ¯ow, fracture, comminution and compaction to generate a protective tribo®lm that retains the interaction in the mild wear regime. If the response leads to microstructural instabilities such as adiabatic shear bands, the near-surface zone consists of stacks of 500 nm layers situated parallel to the slid ing direction. Microcracks are generated below the surface to propagate normally away from the surface though microvoids situated in the layers, until it reaches a depth of 10±20mm. A rectangular laminate debris consisting of a 20±40 layer stack is produced. The wear in this mode is severe