TC4钛合金表面激光合金化Ti-Al-Nb涂层的研究

Research on Ti-Al-Nb Coating by Laser Alloying on TC4 Titanium Alloy

摘要:

以钛铝铌单质元素球磨混合粉末为原料,采用激光合金化技术在TC4钛合金表面成功制备出Ti-Al-Nb合金涂层。分析了涂层的物相组成、组织形貌及成分、显微硬度,并利用YG6球对磨来测试涂层在干摩擦条件下的摩擦磨损性能。结果表明：在激光功率P=1.8 kW,扫描速度V=5 mm/s,光斑直径D=2 mm下制备的涂层整体均匀致密、无裂纹,与TC4基体呈良好的冶金结合；涂层组织主要由Ti₃Al、AlNb₂、α-Ti三种物相组成；Ti-Al-Nb涂层的显微硬度值沿层深方向呈平缓的梯度分布,平均硬度为597 HV,比TC4基体(360 HV)提高了66%；涂层平均摩擦系数为0.45,比TC4钛合金(0.33)降低了27%；涂层的磨损体积为0.044 mm₃,耐磨性是钛合金基体(0.13 mm₃)的2.95倍。

Abstract:

Ti-Al-Nb alloy coating is successfully fabricated on the surface of TC4 titanium alloy by laser alloying using Ti, Al, Nb milled powders as the raw material. The phase composition, microstructure and micro-hardness of the coating are investigated. The friction wear property of the coating is tested with the YG6 ball as counter-body under dry lubrication. The results show that under the laser power 1.8kW,scanning speed 5mm/s and spot diameter 2mm, the coating is uniformdense and crack-free, and it has a good metallurgical combination with the TC4 substrate. Microstructure of the coating mainly consists of Ti₃Al, AlNb₂ and α-Ti. The micro-hardness of the coating (between 580 ~ 630HV) is significantly higher than that of the TC4 matrix (350~360HV). The friction coefficient of Ti-Al-Nb coating is reduced (0.33 vs. 0.45) and the wear resistance is 2.95 times greater than that of the substrate.