钎焊时间对TiH_(2)-65Ni+TiB_(2)钎料钎焊连接TiAl合金接头的影响  

Effect of Brazing Time on TiAl Joint Brazed with TiH_(2)-65Ni+TiB_(2)Filler

作　　者：李力 王一轩[1,2] 罗芬[1,2] 张文涛 赵巍 李小强 LI Li;WANG Yixuan;LUO Fen;ZHANG Wentao;ZHAO Wei;LI Xiaoqiang(School of Materials Science and Engineering,East China Jiaotong University,Nanchang 330013;State Key Laboratory of Performance Monitoring and Protecting of Rail Transit Infrastructure,East China Jiaotong University,Nanchang 330013;National Engineering Research Center of Near-net-shape Forming for Metallic Materials,South China University of Technology,Guangzhou 510641)

机构地区：[1]华东交通大学材料科学与工程学院,南昌330013 [2]华东交通大学轨道交通基础设施性能监测与保障国家重点实验室,南昌330013 [3]华南理工大学国家金属材料近净成形工程技术研究中心,广州510641

出　　处：《机械工程学报》2024年第8期176-185,共10页Journal of Mechanical Engineering

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

摘　　要：基于Kissinger方程计算激活能对机械球磨法制备的(TiH_(2)-65Ni)_(1−x)(TiB_(2))_(x)(x=0~17.70wt.%)复合粉末钎料进行成分优化,并采用TiB_(2)含量为8.16 wt.%的最优钎料在1230℃下钎焊连接Ti-47Al-2Nb-2Cr-0.15B(at.%)合金。系统研究TiAl钎焊接头界面组织和形成机理以及钎焊时间(0~20 min)对接头界面组织和抗剪强度的影响规律,并在详尽分析接头界面组织与抗剪强度关联性基础上揭示TiB晶须的强化机制。结果表明,TiAl钎焊接头界面组织为γ-TiAl/α_(2)-Ti_(3)Al+τ_(3)-Al_(3)NiTi_(2)(层Ⅰ)/τ_(3)-Al_(3)NiTi_(2)+α_(2)-Ti_(3)Al(层Ⅱ)/α_(2)-Ti_(3)Al+τ_(3)-Al_(3)NiTi_(2)+TiB(层Ⅲ)/τ_(3)-Al_(3)NiTi_(2)+α_(2)-Ti_(3)Al(层Ⅱ)/α_(2)-Ti_(3)Al+τ_(3)-Al_(3)NiTi_(2)(层Ⅰ)/γ-TiAl。随着钎焊时间的增加,与钎缝基体热力学相容性较好的TiB晶须长径比先增大而后团聚堆积,钎缝中孔洞先消失而后又出现,时间过长时钎缝中还会存在裂纹和高的残余应力,导致接头抗剪强度先增加后急剧减小。钎焊时间10 min时,接头抗剪强度达到最大值332.87 MPa,以准解理断裂方式脆断于层Ⅱ中。通过改变钎焊时间来调控TiAl合金的溶解和扩散量以期生成较多大长径比的TiB晶须,促使接头组织细化、物相分布均匀,为TiAl合金的推广使用及其高质量钎焊连接提供技术支撑。Based on the activation energy calculated using Kissinger equation,an optimal powder filler containing 8.16 wt.%TiB_(2)is obtained from the mechanical milling(TiH_(2)-65Ni)_(1−x)(TiB_(2))_(x)(x=0-17.70wt.%)powder fillers and used to braze Ti-47Al-2Nb-2Cr-0.15B(at.%)alloy at 1230℃.The interfacial microstructure and formation mechanism of the TiAl brazed joint as well as effect of brazing time varied 0 from 20 min on their interfacial microstructures and shear strengths are systematically investigated.Furthermore,the strengthening mechanism of TiB whiskers is revealed based on detailed analysis of the relationship between interfacial microstructure and shear strength of the TiAl brazed joints.Results show that the interfacial microstructures of the TiAl brazed joints areγ-TiAl/α_(2)-Ti_(3)Al+τ_(3)-Al_(3)NiTi_(2)(layerⅠ)/τ_(3)-Al_(3)NiTi_(2)+α_(2)-Ti_(3)Al(layerⅡ)/α_(2)-Ti_(3)Al+τ_(3)-Al_(3)NiTi_(2)+TiB(layerⅢ)/τ_(3)-Al_(3)NiTi_(2)+α_(2)-Ti_(3)Al(layerⅡ)/α_(2)-Ti_(3)Al+τ_(3)-Al_(3)NiTi_(2)(layerⅠ)/γ-TiAl.With increasing of brazing time,the aspect ratio of TiB whiskers possessing good thermodynamic compatibility with the brazing seam matrix first increase and then agglomerate,the existed microvoids in brazing seam first disappear and then appear again,microcracks and high residual stress occur in brazing seam at overlong brazing time,resulting in increasing first and then a sharp reduction for the shear strength of the TiAl brazed joint.The maximum shear strength of 332.87 MPa for the TiAl brazed joint is obtained when the brazing time is 10 min and it brittlely fractures in layer II in quasi-cleavage mode.More TiB whiskers with large aspect ratio are expected to generate via regulating the dissolution and diffusion of TiAl alloy caused by changing brazing time in order to refine the microstructure and homogenize the phase distribution of the brazed joint,which can provide technical support for the popularization together with application and excellent brazing of TiAl alloy.

关 键 词：钛基粉末钎料 钛铝合金 钎焊时间 界面显微组织 抗剪强度 

分 类 号：TG454[金属学及工艺—焊接]