中文摘要：

采用在Ti-6Al-4V基体表面预置Ti-6Al-4V和硼、碳粉末按比例的混合粉,通过激光束扫描原位制备以钛的硼化物及碳化物为陶瓷相增强颗粒的钛基复合涂层。研究了单道及多道搭接激光工艺参数,包括脉冲频率、脉冲宽度、激光功率、激光扫描速率、预涂层厚度等对复合涂层显微组织及性能的影响。对熔覆样品横截面采用光学显微镜（OM）,扫描电镜（SEM）,X射线衍射仪（XRD）及显微硬度计等进行分析。优化的单道扫描工艺参数为：脉宽3.0 ms,脉冲频率15 Hz,激光线能量约11 J/mm。在此参数下进行多道激光搭接扫描,在Ti-6Al-4V基材上原位生成含有硼化钛及碳化钛硬质增强相及粘接相Ti-6Al-4V的钛基复合涂层,其复合增强相尺寸细小,在涂层中总体上分布均匀;形成的钛基复合涂层没有裂纹与气孔,与基体结合良好,多道扫描样品的显微硬度最高达800 HV,是基材硬度的2倍。优化参数下多道搭接样品的磨损量不到基体磨损量的21%。

英文摘要：

Ti-6Al-4V/B/C mixed powder which pre-pasted on a Ti-6Al-4V substrate was scanned by a 500 W pulsed YAG laser to induced in situ formation of a titanium composite coating contained TiBx and TiC ceramic reinforced phases. The influences of laser processing parameters including pulse frequency （PF）,pulse width （PW）,laser power （P） and scanning speed （V） on the microstructure and properties of the coating were investigated. Microstructure,phase components and micro-hardness of the coating were analyzed by optical microscopy （OM）,scanning electron microscopy （SEM）,X-ray diffraction （XRD） and micro-hardness tester respectively. The optimized processing parameters of a single path laser scanned specimen in this case are as follow：PF=15 Hz,PW=3 ms,laser line energy about 11 J/mm. Multi-path laser scanned specimens were formed under the above processing parameters. TiB and TiC ceramic were formed evenly reinforced in the matrix of Ti-6Al-4V with the morphology of needle,tiny dendrites and disperse particles. No crack and porous are found in the single and multi-path specimens. Metallurgical bonding is formed between the coating and the substrate. The maximum micro-hardness of a multi-path layer is up to 800 HV,which is 2 times of that of the substrate （394 HV）. The wear weight loss of a multi-path laser scanned specimen formed under the optimized processing parameters is 21% less than that of the substrate.