Dry sliding wear of Ti-6Al-4V alloy in air and vacuum

Differences in wear rate, morphology of the worn surface and debris, and the microstructure in subsurface of the Ti-6Al-4V alloy after wear in air and vacuum were compared. The wear rate of Ti-6Al-4V alloy in air is higher than that in vacuum in all the ranges of sliding velocities and applied loads. The wear of Ti-6Al-4V alloy in air is controlled by a combination of abrasion, oxidation and delamination with micro-cracks remaining in subsurface. Under the vacuum condition, the surface layer of Ti-6Al-4V alloy experiences a severe plastic deformation on a great scale, which results in an ultra-fine microstructure.