钎焊温度对Ti-Ni-TiB_(2)钎料钎焊连接γ-TiAl接头的影响  

Effect of Brazing Temperature onγ-TiAl Joint Brazed with Ti-Ni-TiB_(2)Filler Metal

作　　者：冯志雪 王一轩 张文涛 黄慧 李力 FENG Zhixue;WANG Yixuan;ZHANG Wentao;HUANG Hui;LI Li(School of Materials Science and Engineering,State Key Laboratory of Performance Monitoring and Guarantee of Rail Transport Infrastructure,East China Jiaotong University,Nanchang 330013,China)

机构地区：[1]华东交通大学材料科学与工程学院轨道交通基础设施性能监测与保障国家重点实验室,江西南昌330013

出　　处：《热加工工艺》2024年第17期33-37,共5页Hot Working Technology

基　　金：国家自然科学基金资助项目(51865012);江西省自然科学基金资助项目(20202BABL204040);江西省教育厅科学技术研究项目(GJJ170372);国家金属材料近净成形工程技术研究中心开放基金项目(2016005)。

摘　　要：在钎焊温度1170~1210℃、钎焊时间1min的工艺参数下,采用真空悬浮熔炼的Ti-Ni-TiB_(2)铸态钎料钎焊连接Ti-47Al-2Nb-2Cr-0.15B(at%)合金,研究了TiAl合金钎焊接头界面的显微组织,及钎焊温度对接头的组织、抗剪强度的影响,并观察了接头的剪切断口形貌。结果表明,钎焊接头主要由扩散层(Ti_(3)Al)、界面反应层(Ti3Al+Al_(2)NiTi)和中心钎焊层(Al_(2)NiTi+Ti_(2)Ni+TiB_(2)+TiB)3个界面反应层组成。随着钎焊温度的增加,TiAl钎焊接头的扩散层宽度和抗剪强度均先增加后减小,界面显微组织越来越均匀。当钎焊温度为1200℃时,接头抗剪强度最大,达到348 MPa,接头断裂方式为准解理断裂。TiAl钎焊接头中原位自生的TiB晶须使裂纹发生偏转,调节钎缝的热膨胀系数梯度,实现对TiAl钎焊接头的强韧化。Ti-Ni-TiB_(2)cast filler metal prepared by electromagnetic levitation melting was employed to vacuum braze Ti-47Al-2Nb-2Cr-0.15B(at%)alloy under the brazing temperature of 1170-1210℃for 1 min.The interfacial microstructure of the TiAl alloy brazed joints and the effect of the brazing temperature on the microstructure,shear strength of the welded joint were studied,and the shear fracture morphology of the brazed joints were observed.The results show that all the brazed joints are mainly divided into three reaction layers,marked by diffusion layer(Ti_(3)Al),interfacial reaction layer(Ti_(3)Al+Al_(2)NiTi)and center brazing layer(Al_(2)NiTi+Ti_(2)Ni+TiB_(2)+TiB).With the increase of the brazing temperature,the thickness of the diffusion layer and the shear strength of the TiAl brazed joint increase firstly and then decrease,and the interfacial microstructure becomes more uniform.The maximum shear strength of 348 MPa is obtained at 1200℃and the fracture is quasi-cleavage facture.The in-situ synthesized TiB whiskers in TiAl brazeds joint make the crack deflect,and adjust the gradient of thermal expansion coefficient,which realizes the strengthening and toughening of the TiAl brazed joint.

关 键 词：TIAL合金 钎焊温度 抗剪强度 TiB晶须 真空钎焊 

分 类 号：TG454[金属学及工艺—焊接]