| Evolution of Microstructure of Surface Layers of Silver, Copper, Nickel and Aluminum Under Friction in Lubricated Conditions Lev Rapoport1; Alexey Moshkovich2; Inna Popov3; Lev Rapoport1; 1HOLON INSTITUTE OF TECHNOLOGY, Holon, Israel; 2, Holon, Israel; 3THE HEBREW UNIVERSITY OF JERUSALEM, Jerusalem, Israel; PAPER: 373/AdvancedMaterials/Regular (Oral) SCHEDULED: 14:25/Fri. 25 Oct. 2019/Leda (99/Mezz. F) ABSTRACT: The objectives of this work are: to study the evolution of the microstructure of four face-centered cubic metals (Ag, Cu, Ni and Al) after friction in lubricated conditions, to evaluate the effect of stacking fault energy (SFE) on grain size and wear loss [1, 2]. Methods: The deformed microstructures after friction were carefully examined with a field emission scanning electron microscope. Cross sectional transmission electron microscopy. (TEM) lamellae were prepared using a focused ion beam (FIB). Results: Deformation twinning followed by a limited recovery within the surface of Ag led to the formation of relatively thick top layer of ultrafine equiaxial grains. Thermally activated processes for the rearrangement and annihilation of dislocations are accelerated during friction of Cu and Ni due to middle and high SFE and relatively high contact temperature. Steady state values of grain size, ds, and hardness, Hs, during friction are explained by the balance between hardening and dynamic recovery in surface layers, and they strongly depend on the SFE and temperature. Conclusions: The best wear properties of fcc studied metals are determined by high strength and ductility of surface layers during friction. References: [1]A. Moshkovich, I. Lapsker, Y. Feldman, L. Rapoport, Severe plastic deformation of four FCC metals during friction under lubricated conditions, Wear, 386-387 (2017) 49-57. [2] I. Popov, A. Moshkovich, S. R. Cohen, V. Perfilyev, A. Vakahy, L Rapoport, Microstructure and nanohardness of Ag and Ni under friction in boundary lubrication, Wear 404–405 (2018) 62–70. |
