【摘要】 分别利用预涂活性碳粉和 Ti C粉 2种方法对γ-Ti Al基合金 Ti-4 8Al-2 Cr-2 Nb进行激光表面合金化 ,制得了无裂纹、表面光滑、内部组织致密、厚度可达 1 .6mm以上的、以硬质 Ti C树枝晶为增强相的快速凝固“原位”金属基耐磨复合材料表面改性层 ,分别采用 OM,SEM,EDS,XRD等方法分析了激光合金化耐磨表面改性层的显微组织 ,分别在销 -环滑动磨损、Si C纤维刷式高速滑动磨损及微动磨损条件下评价了激光表面改性层的摩擦学性能。结果表明 :采用上述 2种方法所获激光表面合金层组织均匀、与基体间结合为完全冶金结合 ,合金层硬度及在 3种磨损条件下的耐磨性均大幅度提高。激光表面合金化是提高γ-Ti Al合金摩擦性能的一种很有前途的表面改性方法更多还原

【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.更多还原