Y2O3对钛基激光熔覆层组织及性能的影响

针对Ti811钛合金硬度低、耐磨性差的问题，以TC4粉、Ni45A粉和Y₂O₃粉为原料，采用同轴送粉激光熔覆技术在Ti811钛合金表面进行了激光熔覆制备耐磨复合涂层的实验，分析了熔覆层的组织和相组成，测试了熔覆层的显微硬度和摩擦磨损等力学性能。研究表明:复合涂层组织由枝晶TiC、依附生长于枝晶TiC表面的纳米颗粒TiC、生长于基体表面的等轴球形（近球形）TiC、金属间化合物Ti₂Ni、增强相TiB、TiB₂及基体α-Ti组成，所有生成相呈均匀弥散分布状态；涂层中等轴球形（近球形）TiC和Y₂O₃构成了复合相结构，经二维点阵错配度计算表明，Y₂O₃的（111）晶面与TiC的（110）晶面的二维点阵错配度δ=6.54%，因此Y₂O₃可作为TiC的有效异质形核核心细化晶粒；涂层的显微硬度处于HV_0.5 655~700之间，较Ti811基材提高了约1.6~1.8倍；涂层的磨损机制主要为磨粒磨损，摩擦磨损性能较基材显著提升。 

Effect of Y2O3 on microstructure and properties of Ti-based laser cladding layer

Aiming at the problem of low hardness and poor wear resistance of Ti811 titanium alloy, the experiments of laser cladding by synchronous powder feeding laser cladding technology to prepare wear-resistant composite coatings were made. TC4 powder, Ni45A powder and Y₂O₃ powder were used as cladding material. The microstructure and the phase composition were analyzed. The mechanical properties of composite coating such as microhardness and friction and wear properties were tested. The research results show that the coating is made up of dendritic TiC, TiC nanoparticles grown on the surface of dendritic TiC, equiaxed spherical (nearly spherical) TiC grown on the surface of matrix, intermetallic compound Ti₂Ni, reinforced phases TiB, TiB₂ and matrix α-Ti. The phases are uniformly dispersed in the coating. The composite phase structure is consisted of equiaxed spherical (nearly spherical) TiC and Y₂O₃.The two-dimensional lattice mismatch calculation shows that the two-dimensional lattice mismatch between the (111) crystal plane of Y₂O₃ and the (110) crystal plane of TiC is δ=6.54%, which indicates that Y₂O₃ can act as the effective heterogeneous nuclei of TiC to refine grains. The microhardness is between HV_0.5 655 and HV_0.5 700, which is about 1.6 to 1.8 times higher than that of the Ti811 substrate. The wear mechanism of the coating is mainly abrasive wear, the friction and wear properties are significantly improved compared with the substrate.