分别以高纯N2和高纯Ar为保护气体，在TC4钛合金基材表面激光原位合成了TiN/钛基复合涂层。运用X射线衍射仪、扫描电子显微镜和显微硬度计对复合涂层的微观结构和力学性能进行了分析，通过空气电阻炉初步测试了复合涂层的相对高温耐氧化性。结果表明，Ar气氛下原位合成的复合涂层含有较多未完全反应的Ti相，组织均匀性较差，涂层截面显微硬度分布不均；而N2气氛下的原位合成反应比较充分，原位合成复合涂层主要由TiN和Ti3Al两相组成，涂层组织均匀致密，含较多高硬度TiN相，显微硬度自基体至涂层过渡平缓，且平均显微硬度较Ar气氛下复合涂层高约40.7%，600 ℃和800 ℃的相对耐氧化性值分别是TC4基体钛合金的6.83倍和1.94倍，较Ar气氛下的复合涂层提高约17.96%和19.75%。

By utilizing the high-temperature chemical reaction between Ti and AlN, TiN reinforced titanium matrix composite coating is in-situ synthesized on TC4 alloy substrate by laser cladding technique under nitrogen and argon atmosphere, respectively. The microstructure, micro-hardness and relative oxidation resistance of treated samples are examined by X-ray diffraction, scanning electron microscopy, micro-hardness tester and air furnace. The results show that the microstructure and cross section micro-hardness distribution of laser cladding composite coating are more uniform under nitrogen atmosphere than those under argon atmosphere, and the in-situ combustion synthesis reaction is more fully. The composite coating is mainly composed of TiN and Ti3Al phase under nitrogen atmosphere, while it is mainly composed of TiN and α-Ti phase under argon atmosphere. The average micro-hardness of laser in-situ synthesized composite coating changes gradually and increases by 40.7% under nitrogen atmosphere; however, it changes sharply under argon atmosphere. The relative oxidation resistance values of laser cladding composite coating at 600 ℃ and 800 ℃ under nitrogen atmosphere are 6.83 and 1.94 times of those of the TC4 alloy substrate, and increase by 17.96% and 19.75% than those under argon atmosphere, respectively.