保温时间对TiAl合金与镍基合金扩散连接界面组织结构及连接强度的影响

采用纯钛箔做中间层扩散连接TiAl合金与镍基高温合金(GH99).利用扫描电镜、电子探针和X射线衍射等手段对界面产物及接头的界面结构进行分析.结果表明,GH99/Ti界面主要由四个反应层组成,分别为(Ni,Cr)ss,富Ti-(Ni,Cr)ss,TiNi和Ti2Ni.当保温时间较短时,Ti/TiAl界面反应层主要为Ti(Al)ss.延长保温时间,此界面反应层转化为Ti3Al和Al3NiTi2.随着保温时间的延长,TiNi反应层厚度持续增加,而Ti2Ni反应层厚度先增加后减小.随保温时间的延长接头的抗剪强度先增加后减小,然后又增加.由接头断口形貌可以看出,接头主要断裂于Ti2Ni反应层.

Effect of holding time on interface structure and bonding strength of diffusion bonding joint of TiAl and Ni-based alloy

Diffusion bonding of TiAl to Ni-based alloy(GH99) with Ti interlayer was carried out.The reaction products and the interface structures of the joints were investigated by scanning electron microscopy,electron probe X-ray microanalysis and X-ray diffraction.The results show that four kinds of reaction layers are formed at the interface between the GH99 alloy and Ti interlayer,such as(Ni,Cr)ss,rich Ti-(Ni,Cr)ss,TiNi and Ti2Ni.When the holding time is short,Ti(Al)ss layer is formed at the interface between Ti interlayer and TiAl alloy.With the holding time increasing,the Ti(Al)ss reaction layer transformed into Ti3Al and Al3NiTi2.With the holding time increasing,the thickness of TiNi reaction layer increases,while the thickness of Ti2Ni layer increases firstly and then decreases.The shear test results show that the shear strength of the joint increases at first,then decreases,and then increases with the holding time increasing.The fractographs of the joints show that the fracture mainly occurs in the Ti2Ni reaction layer.