钛合金表面激光熔覆复合涂层的熔池行为对微观组织和性能的影响

Effects of the Molten Pool Behavior on Microstructure and Properties of Composite Coating on Titanium Alloy Surface by Laser Cladding

采用5 kW横流CO_2激光器,在TC4钛合金表面激光熔覆原位制备掺Y_2O_3的复合陶瓷涂层。利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、能量散射X谱仪(EDS)对熔覆层组织和物相进行分析;通过维氏显微硬度计对熔覆层和基材显微硬度进行测量。结果表明:随着扫描速度由10 mm/s和8 mm/s增大12 mm/s时,熔覆层表层和中部组织变得更加细化和致密,结合区组织由致密组织结构和稀疏的晶须网状结构变为单一的致密组织结构。当扫描速度为12mm/s时,熔覆层物相为Ti、TiC、TiB_2、Y_2O_3;扫描速度为10 mm/s和8 mm/s时,熔覆层物相为Ti、TiC、TiB、Y_2O_3.扫描速度为10 mm/s和8 mm/s熔覆层的显微硬度提高的主要因素是生成了新的增强相TiB.

The composite coating doped with Y203 was synthesized by alloy with 5 kW continuous wave CO2 laser. The microstructure laser cladding on the surface of TC4 titanium of laser cladding layers and composition of reinforced particles were analyzed using scanning electron microscope（SEM）,energy-dispersive X-ray spectroscopy （EDS） and X-ray diffraction （XRD） ,the micro-hardness of the laser cladding layer was tested using optical microscopy hardness tester. The results show that the microstructure of upper border area and middle zone was refined and dense greatly.Structure of the bonding zone was transformed from compact structure and reticular structure of whisker to compact structure with the scanning speed of 10 mm/s and 8 mm/s to 12 mm/s. When scanning speed was 12 mm/s, phase constituents of the coating were Ti,TiC,TiB2, Y2O3. When Scanning speed was 10mm/s and 8 mm/s,phase constituents of the coating were Ti,TiC,TiB,Y2O3.The micro-hardness of cladding layer gradually reduced with the increase of Scanning speed. And the key factors of hardness are new enhancements TiB.