基于Ti中间层的SiC_(p)/6061-T6Al MMCs低功率激光-TIG复合焊接头组织与性能

Microstructure and Properties of SiC_(p)/6061-T6Al MMCs Joint Manufactured by Low-Power Laser-TIG Hybrid Welding Technology with Ti as Interlayer

以0.1 mm厚的Ti箔作中间夹层,使用低功率激光-TIG复合焊的方式对SiC_(p)/6061-T6Al MMCs进行焊接,并对接头的宏观形貌、显微组织、物相、电阻率、抗拉强度及断口形貌进行分析。结果表明:激光功率对焊缝的成形有着较大影响;Ti箔的加入基本抑制了焊缝中针状Al_(4)C_(3)的生成,并生成TiC增强相以及条状TiAl_(3);焊缝区为等轴晶组织,熔合区为柱状晶组织,热影响区组织变化不明显;随着激光功率的增加,接头的电阻率呈现出增加的趋势,并明显高于母材;在554 W时,接头的抗拉强度可达196.98 MPa,是母材强度的54.71%。接头断口中几乎没有气孔,韧窝中的第二相粒子以TiC为主,接头呈现出以脆性断裂为主的脆-韧性混合断裂特征。

Using Ti foil with thickness of 0.1 mm as the interlayer,SiC_(p)/6061-T6Al MMCs was welded by employing low-power laser-TIG hybrid welding.After welding experiment,the macro morphology,microstructure,phase,resistivity,tensile strength and fracture morphology of the joint were analyzed.The results show that laser power has significant influence on the formability of welding seam.Ti foil can basically suppress the formation of needle-like Al_(4)C_(3) in weld seam.Meanwhile,some new phases such as TiC reinforcement phase and strip-like TiAl_(3) generate in welding seam.The microstructures of weld zone and fusion zone are equiaxed crystal and columnar crystal,respectively.The microstructure in heat-affected zone does not change obviously.The joint resistivity increases with the increasing of laser power and the value of joint resistivity is significantly higher than that in base material.The joint tensile strength achieves 196.98 MPa,which is equal to 54.71%of base material,when laser power of 554 W is applied.There are almost no pores in joint fracture and the second phase particle in dimple is mainly composed of TiC.The joint displays the characteristics of brittle-ductile mixed fracture which is dominated by brittle fracture.