Influence of interstitial oxygen on the tribology of Ti6Al4V

Titanium alloys are used for their good mechanical and corrosion properties, but generally experience poor wear behavior. This can effectively be counteracted by a thermal oxidation treatment, reducing wear significantly. Employing a special sample preparation, we study the transition of tribological properties between thermally oxidized and bulk Ti6Al4V on a single sample. While oxygen signal intensity and hardness followed an exponential decay from the surface to bulk material, tribological results showed a step-like transition from low to high friction and wear with increasing distance from the surface. Low wear was associated with minor abrasive marks, whereas high wear showed as severe adhesive material transfer onto the steel counter body. Besides the mechanical property of hardness, also a change in fracture behavior by interstitial oxygen could influence the observed tribological behavior.