Investigation on the Unlubricated Sliding Tribological Properties of Ti–20Zr–6.5Al–4V Alloy at Elevated Temperatures

In this study, unlubricated sliding friction and wear properties of a recently-developed TiZr-based alloy (Ti–20Zr–6.5Al–4V, TZ20 hereafter) were tested at elevated temperatures ranging from room temperature to 673 K. After the tribological tests, worn surface and cross-section of TZ20 alloy were analyzed to illustrate its wear behavior. The results showed that the wear rate was increased firstly with the ambient temperature, which then decreased when the temperature exceeded critical transition temperature (473 K). Also, the dominant wear mechanisms changed from adhesive wear at room temperature to abrasive wear at 473 K, and then to mild abrasive wear at highest ambient temperature of 673 K. The variations of wear behaviors could be attributed to tribo-oxide layer formed during sliding process. At ambient temperature of 673 K, the tribo-oxide layer formed on the surface was thicker and more compact, and showed more obvious protective role on tribological properties of TZ20 alloy.