TC4表面激光熔覆TiAl合金涂层的工艺和组织性能

为了实现TC4钛合金表面TiAl合金涂层的大面积制备及实际应用，采用激光熔覆的方法在TC4钛基体上制备单道和搭接的TiAl合金涂层。通过表面形貌和界面特征分析了涂层的熔覆质量，对涂层的物相组成与显微组织进行研究，测试了熔覆层界面及搭接层之间的硬度分布。结果表明，涂层与基体之间属于冶金结合，涂层内部没有裂纹和孔隙等缺陷，涂层中Ti/Al主要以TiAl(γ)、Ti₃Al(α₂)以及与微量元素的化合物形式存在，涂层主要由双态组织和片层组织组成，测试得到单道熔覆涂层和搭接涂层平均硬度是基体的1.44倍以上，多道搭接涂层的组织分布相比单道涂层更加均匀；涂层可进行大范围的多道搭接熔覆，证明了TiAl涂层对TC4基体表面改性方法可行性。该研究对于实现涂层的实际应用具有重要意义。

Process and microstructure properties of laser cladding TiAl alloy coating on TC4 surface

To realize the large area preparation and practical application of TiAl alloy coating on the surface of TC4 titanium alloy, a single and overlapped TiAl alloy coating was prepared on the titanium substrate by laser cladding. The cladding quality of the coating was analyzed by surface morphology and interface characteristics, the phase composition and microstructure of the coating were studied, and the hardness distribution between the interface of the cladding layer and the lap layer was measured. The results show that the coating is metallurgical, and there is no cracks and pores in the coating. The Ti/Al mainly exists in the form of TiAl(γ), Ti₃Al(α₂), and trace elements, and the coating is mainly composed of double-state structure and lamellar structure. The average hardness of single cladding coating and lap coating is more than 1.44 times that of substrate. The coating can carry out a wide range of multi-channel lap cladding, which proves the feasibility of the TiAl coating on the surface modification of the TC4 substrate. This study is of great significance for the practical application of the coating.