Interfacial plasticity controls material removal rate during adhesive sliding contact
K Zhao and R Aghababaei, PHYSICAL REVIEW MATERIALS, 4, 103605 (2020).
Adhesive wear is a result of material exchange due to localized adhesive bonding between surface asperities at small scales. It has been recently debated whether a linear wear relation can be observed at the single- asperity level. Using large-scale atomistic simulations, we show that the wear relation is a direct result of the material removal mechanism at the asperity level. In the presence of weak adhesion, sliding is dominated by frictional slipping (i.e., dislocations glide in the contact plane), where occasional atomic cluster detachments and a sublinear wear relation are expected. Alternatively, a linear relation between the volume of detached material and the frictional work can be obtained when bulk plasticity dominants material removal at the asperity tip. Under this condition, high-shear stresses at the contact trigger the migration of misfit dislocations into the asperity bulk, causing severe plastic deformation via dislocation-mediated interface migration. This result highlights that the state of stresses at contact governs the process of material removal and wear relation at the asperity level.
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