Transient liquid phase diffusion bonding of Ti₃Al/TiAl joint using a Ti-Zr-Cu-Ni-Fe interlayer

Transient liquid phase diffusion bonding of Ti₃Al-based alloy to TiAl intermetallic was conducted and a newly designed Ti-Zr-Cu-Ni-Fe alloy was used as interlayer. The joint microstructure was examined using a scanning electron microscope (SEM) equipped with an electron probe micro-analyzer (EPMA), the phase constitution was identified using an X-ray diffraction (XRD) spectrometer detected on the fractured surface. The results show that the Ti₃Al/TiAl joint mainly consists of Ti-rich phase, Ti₂Al layer, α₂-Ti₃Al phase and residual Al dissolved interlayer alloy dissolved with Al. The dissolution and inter-diffusion between base metal and interlayer become stronger with the increase of the bonding temperature. And meantime the Ti₂Al is thickened and the amount of residual interlayer at the central part of the joint is decreased. The shear test results indicate that in the range of 880~1010℃ the increase of bonding temperature is beneficial to the joint strength. The maximum shear strength of Ti₃Al/TiAl joint reached 502 MPa at room temperature and the shear strength was maintained at 196 MPa in 500℃.