AVS 63rd International Symposium & Exhibition
    Tribology Focus Topic Wednesday Sessions
       Session TR+AS+NS+SS-WeA

Invited Paper TR+AS+NS+SS-WeA9
Plasticity Controlled Friction and Wear in Single-Asperity Contacts

Wednesday, November 9, 2016, 5:00 pm, Room 101A

Session: Nanoscale Wear: Applications to Nanometrology and Manufacturing
Presenter: Izabela Szlufarska, University of Wisconsin - Madison
Authors: I. Szlufarska, University of Wisconsin - Madison
L. Zhao, University of Wisconsin - Madison
A. Li, University of Wisconsin - Madison
C. Tangpatjaroen, University of Wisconsin - Madison
D. Grierson, University of Wisconsin - Madison
Correspondent: Click to Email
One of the critical challenges in designing materials with superior tribological properties is the current lack of understanding of the microstructural evolution that takes place in sliding contacts. Phenomena that contribute to such evolution are grain growth and refinement, evolution of dislocation networks, and interaction of dislocations with interfaces. In this talk I will discuss examples of how we use multi-scale simulations and atomic force microscopy (AFM) experiments to determine the role of microstructural evolution and plastic deformation in friction and wear. Specifically I will discuss: (i) Our developments of a continuum model that couples grain growth, plastic deformation, and mechanics. This model combines for the first time the phase field method, crystal plasticity, and finite element analysis of mechanical contacts, and parameters for this model are determined from atomistic simulations and experiments. The new model is capable of simulating deformation at strain rates comparable to those encountered in AFM experiments. (ii) Results from our molecular-level simulations on the effects of dopants on strength and wear resistance of nanostructured metal alloys. (iii) Discovery from our complementary AFM and nanoindentation experiments that, although a harder material (silicon carbide) is typically more wear resistant than a softer material (silicon), this trend can be reversed with smaller contact sizes. The contact pressure is the same in both sets of experiments, and both are carried out in the regime where a plastic zone is well-developed. We demonstrate that this surprising finding is due to a transition from abrasive to adhesive wear, which for the first time is observed in single-asperity contacts. Our results show that surface chemistry can have a significant effect on sub-surface plastic deformation.