关键词: γ-TiAl金属间化合物, 激光表面合金化, 摩擦学性能

Abstract: TiAl intermetallic alloy is regarded as one of the promising candidate elevated-temperature structural materials for the aerospace industries because of its low density, high specific strength and toughness. Tribological properties of γ-TiAl base alloy need to be improved when applied as tribological components. In this paper, laser surface alloying with carbon and TiC powder pre-coatings respectively was utilized to improve the tribological properties of γ-TiAl intermetallic alloys. Wear-resistant "in-situ" composite coatings reinforced by rapidly solidified TiC dendrites were successfully produced on substrate of the γ-TiAl intermetallic alloy with smooth coatings surface, free from cracks and with coatings thickness up to 1.6mm. Microstructure of the laser surface alloyed coatings was characterized by OM, XRD, EDS and SEM as functions of laser surface alloying variables. Tribological properties of the laser surface alloyed composite coatings were evaluated under block-on-ring sliding, fretting and brush-on-disc high-speed sliding wear conditions. The microstructure within the whole laser surface alloyed coatings is homogeneous and the bonding to the substrate is pure metallurgical. The hardness and the tribological properties under all the three wear conditions are enhanced considerably. The results demonstrated that laser surface alloying is a promising surface modification method for improving the tribological properties of γ-TiAl intermetallic alloys.

Key words: C-TiAl intermetallic alloy, laser surface alloying, t ribologica l properties