Dry Sliding Tribology of γ-TiAl-Based Alloys

Abstract

Incorporating TiAl alloys in engine applications offers benefits including reduced fuel consumption and improved efficiency. However, understanding the wear behaviour of these materials is an important consideration due to their use in harsh environments involving movable parts. This study investigated the wear behaviour and mechanisms of Ti–48Al–2Nb–0.3Si-1Sn (TiAl–S1) together with Ti–48Al–2Nb–0.3Si (TiAl–S0) as a reference alloy against an alumina ball. Scanning electron microscopy (SEM) analysis showed that the addition of Sn refined the lamellar structure from 216 μm to 130 μm and promoted more uniform deformation. SEM observations also indicated that abrasive wear is the dominant mechanism in the TiAl alloys. The TiAl–S1 exhibited lower hardness, resulting in deformation of wear debris and promoting third body acting as a lubricant. SEM-EDS revealed that the tribo-layer and wear debris originated from the TiAl materials rather than the counterpart alumina material. Both alloys demonstrated noble wear resistance, with a wear rate of 7.542 × 10−6 mm3/Nm for TiAl–S1 and 6.729 × 10−6 mm3/Nm for TiAl–S0. Even though both TiAl alloys experienced abrasive wear mechanisms, the addition of Sn emerges as a promising alloying strategy, for enhancing ductility without significantly increasing material loss.