镁/镍/钛激光熔钎焊接头组织性能研究  

Microstructure and Properties of Mg/Ni/Ti Laser Welding-Brazing Joint

作　　者：陈国财 程东海[1] 王德 刘亚明 Chen Guocai;Cheng Donghai;Wang De;Liu Yaming(School of Aeronautical Manufacturing Engineering,Nanchang Hangkong University,Nanchang 330063,China)

机构地区：[1]南昌航空大学航空制造工程学院,江西南昌330063

出　　处：《稀有金属》2024年第1期35-42,共8页Chinese Journal of Rare Metals

基　　金：国家自然科学基金项目(51965045,51901090)资助。

摘　　要：通过预置厚度为0.1 mm的Ni片作为中间层,将尺寸均为120 mm×60 mm×1 mm(长×宽×高)的AZ31B镁合金板和TC4钛合金板进行激光熔钎焊搭接试验,对镁/镍/钛接头的界面宏观形貌和微观组织进行分析,探究界面结合区域对接头力学性能的影响。结果表明:预置Ni片后的接头焊缝成形良好。在最佳工艺窗口为“激光功率P=1250~1350 W,焊接速度v=17~19 mm·s^(-1)”时,接头力学性能较好。随着激光功率和焊接速度的增大,接头的拉剪强度均呈现出先增大后减小的趋势,拉剪强度最高可达94.91 MPa。接头焊缝区由镁侧焊缝、钛侧焊缝和金属间化合物(IMC)层组成。镁、钛两侧焊缝间的界面结合面积大小及元素间反应生成的IMC层是提高镁/镍/钛接头力学性能的关键:Ni元素与Mg,Ti元素进行了良好的冶金反应,Ni与Mg,Al在镁侧焊缝生成弥散分布的Mg_(2)Ni+AlNi镁侧化合物层,Ni与Ti在钛侧焊缝生成均匀分布的Ti_(2)Ni钛侧化合物层;随着激光功率的增大和焊接速度的减小,接头单位时间内的热输入量增高,钛侧母材熔化量增多,使得镁钛焊缝界面结合面积增大,Ni在两侧焊缝中的扩散能力增强;当两侧焊缝成形良好且无明显裂纹时,接头力学性能更佳。With the rapid development of aerospace industry,magnesium/titanium dissimilar metal connectors have been widely used in aerospace industry.However,the joint between Mg alloys and Ti alloys is restricted by their huge differences in physical and metallurgical properties.The melting point of magnesium and titanium are 649 and 1668℃respectively and the boiling point of magnesium is 1090℃,hence both of Mg and Ti alloys are difficult to remain in molten state at the same time.The severe evaporation of magnesium would occur when using the conventional fusion welding techniques.In addition,no mutual diffusion or reaction occurs during solidification process due to the metallurgical immiscibility of Mg/Ti,which make it difficult to obtain high-quality fusion welded joint when connecting magnesium and titanium.In order to solve the problem that Mg/Ti dissimilar metals do not dissolve or react with each other and realize the metallurgical combination of Mg/Ti dissimilar metals,the laser welding experiment of Mg/Ni/Ti plate fixed on the worktable was carried out with IPG ylr-4000 fiber laser.The base metals adopted in the present work were 1.0 mm thick AZ31B magnesium alloys and 1.0 mm thick TC4 titanium alloys with dimension of 120 mm×50 mm.Ni foil with thickness of 0.1 mm and purity of99.9%was added as intermediate layer.Laser welding joints with different microstructures and properties were obtained by adjusting the laser power and welding speed.Properties of Mg/Ni/Ti laser welding-brazing joints with different welding parameters were tested by WDW-100 microcomputer controlled electronic universal testing machine.Samples with different welding parameters were cut perpendicular to the weld seam by electrical discharge machining (EDM).Metallographic specimens were prepared by mounting in denture base resins and then grinded by different SiC grades abrasive paper and polished a mirror-like surface by 3.5μm diamond suspension.The weld appearances and microstructures were examined by optical microscopy (OM) and scannin

关 键 词：预置Ni片 激光熔钎焊 界面结合 金属间化合物 元素扩散 

分 类 号：TG442[金属学及工艺—焊接]