Abstract: During low-altitude flight, take-off, and landing, aircraft compressor blades are vulnerable to significant erosion caused by airborne dust and sand particles propelled by high-speed airflow. In this study, Ti/TiAlN multilayer coatings with a gradient transition composite soft/hard alternating laminated structure were prepared on the surfaces of titanium alloys using arc ion plating technology. The mechanical properties and multi-angle resistance to foreign object damage of the coatings were evaluated in order to elucidate the deformation and strengthening mechanisms of the multilayer structure. The findings revealed that the coatings exhibited an adhesion strength exceeding 72 N, a hardness and elastic modulus of 25.1 GPa and 304.3 GPa, respectively. The impact depth of the coatings was reduced by over 20 % compared to the uncoated substrate. The enhanced resistance of the coatings to foreign object damage is primarily attributed to the hard TiAlN layer, which exhibits resistance to the cutting action of low-angle erosion particles. Concurrently, the soft Ti layer facilitates deformation at higher angles, promoting plastic deformation. Furthermore, the ceramic layer evidenced the decrease of stress concentration through mechanisms including grain refinement, transgranular microcrack propagation, and intergranular extension. The ductile layer served to enhance toughness by dissipating strain energy through mechanisms such as deformation twinning and dislocation generation.

Key words: Multilayer coatings, Mechanical properties, Multi-angle erosion, Foreign object impact, Failure mechanism