Microstructure evolution of TLP bonding interface for Ti₃Al based alloy

With Ti-37.5Zr-15Cu-10Ni (%) amorphous foil as the brazing filler metal,the microstructure evolution of the TLP(Transient liquid phase) diffusion bonding interface for Ti₃Al-based alloys was studied. The Ti and Nb elements diffuse into the brazing filler and the Ni,Cu,Zr elements diffuse into the matrix to drive the interface evolution. At 930℃ the metallurgical bonding is achieved after holding time of 5 min. The TiNi₃ (Cu,Zr) compound in the shape of strip is precipitated after holding time of 15 min. This compound will get refined and dispersed with the holding time being longer. When the holding time lasts until to 120-200 min,the interface microstructure evolved to the coarse and homogeneous Widmanstaten structure. Since the compound character is affected by the holding time,it can be an effective method to control the microstructure and strengthen the interface by controlling the holding time.