Dry Sliding Wear Characteristics of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si Alloy at Various Sliding Speeds

Dry sliding wear behavior of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si (hereafter called TC11) alloy was investigated under various sliding speeds and distances. TC11 alloy presented marked variations of the wear rate with an increase of sliding speed from 0.5 to 4 m/s. Especially at high loads, a severe-to-mild wear transition occurred with the climax at 2.68 m/s, the lower values were at 0.5 to 1.5 m/s, and the lowest point was at 4 m/s. TC11 alloy also presented a mild-to-severe wear transition at 2.68 m/s with an increase of sliding distance, but not at the others. With a thorough examination for worn surfaces, subsurfaces and wear debris, the distinct characteristics were noticed to correspond to the wear behavior in various conditions. The highest wear rate at 2.68 m/s and the lowest wear rate at 4 m/s, respectively, corresponded to no oxides and large wear debris particles as well as more oxides and small wear debris particles. The tribo-oxides formed at room temperature were suggested to be protective, which seemed to be contradictory to the popular view that tribo-oxides of titanium alloys possess no wear-reducing effect.