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MM: Fachverband Metall- und Materialphysik
MM 70: Mechanical Properties II
MM 70.1: Talk
Thursday, March 23, 2017, 17:00–17:15, IFW D
The Origin of Microstructural Discontinuities underneath a Tribologically Loaded Surface — •Christian Greiner1, Zhilong Liu1, Reinhard Schneider1, Lars Pastewka1, and Peter Gumbsch1,2 — 1KIT, Kaiserstrasse 12, 76131 Karlsruhe — 2Fraunhofer Institute for Mechanics of Materials IWM, Woehlerstrasse 12, 79108 Freiburg, Germany
Frictional loading of a metal surface induces microstructural changes underneath the surface. A typical tribo-induced microstructure displays distinct discontinuities parallel to the surface which separate the near surface layer from the bulk. By systematically decreasing the number of passes of a sapphire sphere sliding over high-purity copper, we find that the origin of the microstructural discontinuity is already laid after the first sliding pass even for very mild sliding conditions. A distinct dislocation structure is formed 100-150 nm under the surface. This distinct dislocation self-organization is attributed to a sign change in the stress field underneath the sliding indenter. The dislocation structure evolves into the known microstructural features with increasing number of sliding passes. Consequently, the microstructure and mechanical properties of the surface layer are determined in the very first loading pass. Control of the initial tribological loading could therefore be exploited to precondition interfaces for superior tribological properties.