Mechanics of Deformable Solids
Moshkovich A., Perfilyev V., Lapsker I., Meshi L., Rapoport L.
ALEXEY MOSHKOVICH, Ph.D., Holon Institute of Technology, Holon. 5810201, Israel, e-mail: alexeym@hit.ac.il
VLADYSLAV PERFILYEV, Ph.D., Holon. Institute of Technology, Holon, 5810201, Israel, e-mail: vladper@hit.ac.il
IGOR LAPSKER, Ph.D., Holon Institute of Technology, Holon 5810201, Israel, e-mail: lapsker@hit.ac.il
LOUISA MESHI, Ph.D., Department of Materials Engineering, Ben Gurion University of the Negev, Beer Sheva 84105, POB 653, Israel, e-mail: louisa@bgu.ac.il
LEV RAPOPORT, Prof., Ph.D. (corresponding author), Holon Institute of Technology, Holon, 5810201, Israel, e-mail: rapoport@hit.ac.il
Superplastic deformation of α/β brass under friction in lubrication conditions
Copper (Cu) and its alloys are widely used for various moving machine parts. Friction and wear of machine parts is mainly determined by the microstructure and plastic deformation of surface layers. The dislocation structure and plastic deformation of α/β brass after friction in boundary lubrication (BL) conditions were studied. The friction of brass was attributed to superplastic deformation (according to our estimation close to 500%) in thin surface layers of the α-phase grains. Intragranular slip, as the accommodating mechanism, occurred in α-phase, whereas a little deformation was observed in the β-phase. The accommodation of sliding was accompanied by growth and coalescence of voids, formation and propagation of cracks, leading finally to delamination of the wear particles. The equivalent strain vs. the depth was evaluated. Large deformation of thin surface layers led to formation of the nanocrystalline structure (d = 35 nm). The SPD of surface layers is accompanied by formation of thin shear bands practically parallel to the direction of friction. The thickness of wear particles was found to be close to the thickness of shear bands. The hardness of surface layers of Cu slightly decreased, while the hardness of brass increased with an increasing the contact temperature. Deformation hardening of brass was significantly larger than for Cu.
Key words: brass; microstructure; plastic deformation; friction.
