Microstructural evaluation of Hastelloy-X transient liquid phase bonded joints:Effects of filler metal thickness and holding time  

焊料厚度和保温时间对瞬间液相连接Hastelloy-X合金接头显微组织演化的影响

作　　者：A.MALEKAN S.E.MIRSALEHI M.FARVIZI N.SAITO K.NAKASHIMA A.MALEKAN;S.E.MIRSALEHI;M.FARVIZI;N.SAITO;K.NAKASHIMA(Ceramic Division,Materials and Energy Research Center,P.O.Box 14155-4777,Tehran,Iran;Department of Materials and Metallurgical Engineering,Amirkabir University of Technology(Tehran Polytechnic),Tehran 15875-4413,Iran;Department of Materials Science and Engineering,Kyushu University,744,Motooka,Nishi-ku,Fukuoka 819-0395,Japan)

机构地区：[1]Ceramic Division,Materials and Energy Research Center,P.O.Box 14155-4777,Tehran,Iran [2]Department of Materials and Metallurgical Engineering,Amirkabir University of Technology(Tehran Polytechnic),Tehran 15875-4413,Iran [3]Department of Materials Science and Engineering,Kyushu University,744,Motooka,Nishi-ku,Fukuoka 819-0395,Japan

出　　处：《Transactions of Nonferrous Metals Society of China》2022年第5期1548-1558,共11页中国有色金属学报（英文版）

摘　　要：Transient liquid phase(TLP)bonding was investigated in Hastelloy-X samples with different filler metal thicknesses(20,35,50,65,and 100μm)and holding time(5,20,80,320,and 640 min)to obtain optimum bonding parameters.Microstructural evaluations using electron probe microanalysis(EPMA)and electron backscattered diffraction(EBSD)show that the central eutectic phases present in the athermally solidified zone(ASZ)are Ni_(3)B,Ni_(2)Si,and CrB,and the precipitates formed in the diffusion-affected zone(DAZ)are MoB,CrB_(2),and Mo_(2)B_(5).According to the results,decreasing the filler thickness as well as increasing the holding time helps realize the completion of isothermal solidification and reduction in the density of precipitates in the DAZ,leading to a joint with more uniform properties.Diffusion of boron and silicon to longer distances with increasing holding time causes the removal of Cr-rich borides in the DAZ and the formation of Mo-rich silicide at the joint interface.Decrease in hardness of ASZ and DAZ due to the elimination of brittle phases in these zones during long holding time causes more uniform hardness distribution in the joint area.The best results are obtained for the sample joined with the 35μm-thick filler metal for 640 min holding time.研究不同焊料厚度(20,35,50,65,100μm)和保温时间(5,20,80,320,640 min)下Hastelloy-X样品的瞬间液相(Transient liquid phase,TLP)连接,以获得最优连接参数。电子探针显微分析(EPMA)和电子背散射衍射(EBSD)显微组织分析表明,非热凝固区(ASZ)中心的共晶相为Ni_(3)B、Ni_(2)Si和CrB,扩散影响区(DAZ)形成MoB、CrB_(2)和Mo_(2)B_(5)析出相。结果表明,减小焊料厚度、增加保温时间有助于完成等温凝固、降低DAZ中析出相的密度,这使接头性能更加均匀。随着保温时间的增加,硼和硅的扩散距离变长,导致DAZ中富Cr硼化物消除,并在接头界面形成富Mo硅化物。随着保温时间的延长,ASZ和DAZ中脆性相的消除导致其硬度降低,使得接头区域的硬度分布更加均匀。最优连接参数为:金属焊料厚35μm,保温时间640 min。

关 键 词：Hastelloy-X transient liquid phase(TLP)bonding microstructure filler metal electron probe microanalysis(EPMA) electron backscattered diffraction(EBSD) 

分 类 号：TG407[金属学及工艺—焊接]