Nanoscale incipient asperity sliding and interface micro-slip assessed by the measurement of tangential contact stiffness

Experiments with a multidimensional nano-contact system have shown that, prior to kinetic frictional sliding, there is a significant reduction of the tangential contact stiffness relative to the elastic prediction. The reduction occurs at contact sizes below about 50-200 nm for aluminum single crystals and several other materials. Using a cohesive interface model, we find that this reduction corresponds to a transition from a small-scale-slip to large-scale-slip condition of the interface. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.