目的 研究Ti811合金表面激光熔覆涂层的微观组织及磨损性能。方法 利用激光熔覆技术，在Ti811合金表面激光熔覆原位合成了TiC+TiB2增强镍基复合涂层。利用X射线衍射仪（XRD）、扫描电镜（SEM）、电子探针（EPMA）、显微硬度计和摩擦磨损试验机，系统地研究了熔覆层的物相组成、显微组织、显微硬度及摩擦磨损性能，并利用二维点阵错配度理论对TiC的细化机理进行分析。结果 激光熔覆涂层与基体呈良好的冶金结合，熔覆层生成物相主要由TiC、TiB2、Ti2Ni和γ-Ni组成，其中TiC呈等轴枝晶状和花瓣状，Y2O3的（111）面与TiC的（110）面之间的二维点阵错配度为6.813%，Y2O3作为TiC的非均质形核核心为中等有效。熔覆层的平均显微硬度为913.93HV0.5，约为基体Ti811硬度的2.4倍。熔覆层摩擦系数稳定在0.45~0.52之间，磨损机理主要为粘着磨损与磨粒磨损。结论 采用激光熔覆技术能够在Ti811合金表面成功制备Ni基复合增强涂层。熔覆层中Y2O3颗粒具有细晶强化、弥散强化、增加形核率的作用，熔覆层具有较高的显微硬度与良好的耐磨损性能。

The work aims to study the microstructures and wear resistance of laser cladding coating on Ti811 alloy surface. A Ni-based composite coating reinforced by in situ synthesized TiC and TiB2 was prepared on Ti811 by laser cladding. Phase, mi-crostructure, microhardness and wear resistance of the cladding coating were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron probe microscopic analyzer (EPMA), Vickers hardness tester, and friction wear testing ma-chine. Moreover, the refinement mechanism of TiC was also discussed by the two-dimensional lattice misfit theory. A good metal-lurgical bonding was formed between the laser cladding coating and substrate, the main phase composition of the cladding coating included TiC, TiB2, Ti2Ni and γ-Ni, of which TiC was equiaxial dendrite and petal shape, and the two-dimensional lattice misfit between the face (001) of Y2O3 and the face (110) of TiC was 6.813%, which indicated that Y2O3 as the heterogeneous nuclei of TiC was middle-effective. The average microhardness of the cladding coating was 913.93HV0.5, about 2.4 times than that of the substrate. The friction coefficient of the cladding coating kept stable between 0.45 and 0.52, and the main wear mechanisms were adhesive wear and abrasive wear. The Ni-based composite coating can be successfully prepared by laser cladding technology on Ti811 alloy surface. Y2O3 particles in the cladding coating have the effects to strengthen fine crystal, reinforce dispersion and in-crease nucleation rate. Meanwhile, microhardness and wear resistance of the cladding coating are increased dramatically.