Tribological properties of the uncoated and aluminized Ti–48Al–2Cr–2Nb TiAl alloy at high temperatures

Abstract

Al-rich phases are often recommended as potential coating candidates for TiAl alloys and their application as a turbine blade material in aero engines. As high wear resistance is also required for this application, the tribological properties of Al-rich phases need to be investigated with a focus on the influence of temperature. Therefore, a comparative investigation of the dry sliding wear behavior of the uncoated and aluminized Ti–48Al–2Cr–2Nb TiAl alloy was conducted between room temperature and 600 °C in air. While the uncoated TiAl alloy suffers from successively increasing wear rates with increasing temperature, the aluminized alloy shows lower wear rates up to 400 °C. However, barely any positive influence on the required wear protection can be observed at 600 °C due to partial failure of the coating. Wear mechanisms of both the uncoated and aluminized samples are characterized by high material transfer to the counterpart material, the Ni-based alloy IN718. This phenomenon is caused by the tendency for strong adhesive bonding between the two metallic counterparts and becomes even more pronounced with increasing temperature.