Investigation on wear mechanism of thermochemically fabricated W-Cu composites

W-25 wt%Cu nanocomposite powder was prepared by thermochemical co-precipitation method. Consolidation procedure was performed at 1200 degrees C under hydrogen atmosphere and led to the densification up to 98% theoretical density Wear test was carried out with a pin-on-disc apparatus under 5, 10, and 15 N normal loads. Volume of the lost material and also the wear rate increased by increasing the normal load while, friction coefficient showed a reverse record and decreased by increasing the load. Formation of mechanically mixed layers (MMLs) and their successive deformation and work hardening was found to be the origin of the friction coefficient decrease at increased normal loads. At low normal load just shallow scuffs and particle pull out were observed in the surface and sub-surface studies of the wear sample. But at higher normal loads large flakes of the matter were cut off and lost accompanying deep grooves and branched cracks. Continuous cyclic deformation at sufficiently high normal loads, could give rise to MML formation, sub-surface deformation, crack nucleation and propagation, and finally delamination of the composite (C) 2010 Elsevier B.V. All rights reserved.