钛基稀土激光熔覆层组织细化机制及性能

采用通快TruDisk 4002光纤激光器在TC4合金表面分别制备了0wt% Y₂O₃和3wt% Y₂O₃的TC4+Ni45+Co-WC钛基耐磨复合涂层。利用XRD、SEM、EDS、EPMA、显微硬度计和摩擦磨损试验机等分析了涂层组织、显微硬度和摩擦学性能。结果表明，两种涂层表面均无裂纹孔隙等缺陷，且生成相一致，主要包括TiC、TiB₂、Ti₂Ni、WC和α-Ti；0wt% Y₂O₃涂层组织存在明显偏析，析出相尺寸粗大且方向性明显；3wt% Y₂O₃涂层组织呈均匀弥散状态分布，细化特征明显；经Bramfitt二维点阵错配度计算，（100）_Y2O3和（100）_Ti2Ni、（111）_Y2O3和（110）_TiC、（110）_Y2O3和（1010）_TiB2间的错配度分别为5.75%、6.72%和10.10%，Y₂O₃作为异质形核核心对Ti₂Ni、TiC和TiB₂的细化能力依次为Ti₂Ni > TiC > TiB₂；0wt% Y₂O₃和3wt% Y₂O₃涂层显微硬度分别为600~630 HV_0.5和470~480 HV_0.5，较基材分别提高了约62%和26%；3wt% Y₂O₃涂层耐磨减摩性最优，其磨损体积和摩擦系数较0wt% Y₂O₃涂层分别下降了约47.8%和5.0%，磨损机制主要为磨粒磨损。

Microstructure refinement mechanism and properties of Ti-based rare earth laser cladding layers

TC4+Ni45+Co-WC Ti-based wear-resistant composite coatings with different Y₂O₃ additions (0wt% and 3wt%) were prepared on the surface of TC4 alloy by using TRUMPF TruDisk 4002 fiber laser. The microstructure, microhardness, and tribological properties of the coatings were analyzed by using XRD, SEM, EDS, EPMA, microhardness tester, and friction and wear apparatus. The results show that there are no cracks, pores, and other defects on the two coating surfaces, and the formation phases are consistent, mainly including TiC, TiB₂, Ti₂Ni, WC and α-Ti. In 0wt%Y₂O₃ coating, there is an obvious microstructure segregation and the size of the precipitated phase is coarse with the evident dendrite orientation. In 3wt%Y₂O₃ coating, the microstructure is uniformly dispersed and the refinement effect is significant. According to Bramfitt two-dimensional lattice misfit calculation, the misfit between (100)_Y2O3 and (100)_Ti2Ni, (111)_Y2O3 and (110)_TiC, and (110)_Y2O3 and (101-0)_TiB2 are 5.75%, 6.72% and 10.10%, respectively. The ability of Y₂O₃ acting as an effective heterogeneous nucleus to refine Ti₂Ni, TiC and TiB₂ is Ti₂Ni > TiC > TiB₂. The microhardness of 0wt%Y₂O₃ coating and 3wt%Y₂O₃ coating is 600-630 HV_0.5 and 470-480 HV_0.5, which is 62% and 26% higher than that of the substrate. 3wt%Y₂O₃ coating shows the best wear resistance and anti-friction. The wear volume and friction coefficient are 47.8% and 5.0% lower than those of 0wt%Y₂O₃ coating, and the wear mechanism is mainly abrasive wear.