2、NaF和Na2SiF6作為活性劑對TC4鈦合金進行活性激光焊接，在焊接過程中利用高速攝像機采集焊件上方的光致等離子體圖像，焊后借助光學顯微鏡測量焊縫熔深和熔寬，利用EBSD觀察分析焊縫顯微組織，采用能譜儀測試焊縫元素組成，測試接頭硬度和抗拉強度。結(jié)果表明，由于活性劑改變了焊件表面狀態(tài)和壓縮光致等離子體面積從而提高了激光吸收率，這使得焊縫熔化區(qū)面積增加；活性劑均可以使未熔透焊縫的熔深增加，正面熔寬減小，熔透焊縫正面熔寬減小，中部和背面熔寬均增加，3種活性劑中Na2SiF6對TC4鈦合金激光焊焊縫成形的影響最明顯；活性劑對焊縫下部顯微組織影響不大，涂敷CaF2和NaF后，焊縫上部β柱狀晶的生長方向與未涂敷焊縫β柱狀晶生長方向都指向焊縫表面，涂敷Na2SiF6焊縫上部β柱狀晶的生長方向指向焊縫中心。涂覆CaF2焊縫針狀馬氏體α′形態(tài)變化不明顯，涂敷NaF的針狀馬氏體α′變得稍細，而涂敷Na2SiF6的針狀馬氏體α′變得短且細，較涂敷CaF2和NaF的焊縫變化最明顯。涂敷Na2SiF6的接頭抗拉強度提高約12.5%，從改善焊縫成形和提高接頭力學性能考慮，Na2SiF6可作為TC4鈦合金激光焊的首選活性劑。;CaF2, NaF and Na2SiF6 were chosen as activating fluxes for laser welding of Ti6Al4V (TC4) alloy. During the welding process, the laser-induced plasma images above the weldment were captured with a high-speed camera. After welding, the weld penetration and the width of the weld were measured and the microstructure was observed by an optical microscope. Then, the morphology of acicular martensite in the weld was studied by EBSD, and the element composition of the weld was determined by energy spectrometer. The hardness and tensile strength of the joints were tested. The results show that the activating fluxes change the surface state of the weldment and compress the laser-induced plasma area, thereby increasing the laser absorptivity and the area of the weld melting zone. Besides, all the activating fluxes can increase the penetration depth and reduce the top weld width of the partial penetration weld, and reduce the top weld width while increase the middle and bottom weld widths of the penetration weld. It is also found that for the welds coated with CaF2, NaF andwithout activating fluxes, the β columnar crystals on the upper part of the welds all grow towards the weld surface, while for the welds coated with Na2SiF6, the β columnar crystals on the upper part of the welds grow towards the weld center. The activating fluxes have no obvious effect on the growing direction of the β columnar crystals of the lower part of the weld. Na2SiF6 can significantly refine the acicular α′ in the β columnar crystals of the upper part of the welds in the laser welding of TC4 alloy. The tensile strength of the welded joint coated with Na2SiF6 is increased by 12.5%. Compared with other activating fluxes, Na2SiF6 has the most prominent effect on the weld formation and mechanical property of the laser welded TC4 titanium alloy, and thus it can be used as the most preferred activating flux."/>