In-situ synthesized Ti5Si3-Ti2AlC reinforced TiAl composite with enhanced tribological properties

Abstract

Herein, the TiAl composite with Ti₅Si₃ and Ti₂AlC particles reinforced was designed to improve its tribological properties at different temperatures, in which was in-situ fabricated by spark plasma sintering using Ti-48Al-2Nb-2Cr alloy with addition of SiC particles. Moreover, the Ti₅Si₃ particles were predominantly distributed at the lamellar colony boundaries forming a discontinuous network structure, while Ti₂AlC particles primarily precipitate at the interfaces of α₂/γ lamellae. The tribological results exhibited the friction coefficient of TiAl composite was lower than that of TiAl alloy at room-temperature and elevated temperatures (650, 750, and 850 °C). The friction coefficients were 0.48 and 0.54 for TiAl composite at room-temperature and 850 °C, reduced by 21.3 % and 12.9 % compared to TiAl alloy. However, the wear rate was reversed at 750 and 850 °C indicating the change of wear mechanism. The abrasive and ploughing wear transform to plastic deformation, oxidation wear and adhesive wear at 650 °C for pure TiAl alloy, and the transformation temperature was 750 °C for TiAl composite. It revealed that TiAl composite showed superior wear resistance at different temperatures, which mainly attributed to the Ti₅Si₃–Ti₂AlC particles refined microstructure and enhanced microhardness, strength, and oxidation resistance.