Interfacial Structure and Properties of Reactive Brazing Joints of TiAl/Ni-based Alloy

TiAl alloy and Ni-based alloy were joined by vacuum reactive brazing using Ti foil as the interlayer. Interfacial microstructure and formation phases of the brazed joint were investigated by means of scanning electron microscope and electron probe microanalysis, and shear strength of the joint was determined. The results show that the brazed joint is mainly composed of Ti-ss and Ti2Ni when brazed at 960 degrees C; when the brazing temperature increases from 960 degrees C to 1000 degrees C, Ti-Al and Al-Ni-Ti compounds form in the brazing seam and the typical interface structure of the brazed joint is GH99/(Ni,Cr)(ss)/Ti2Ni+AlNi2Ti+TiNi/Ti3Al+Al3NiTi2/Ti3Al+Al3NiTi2/TiAl. Further increasing the brazing temperature results in excessive growth of Ti3Al and Al3NiTi2 phase, which reduces the joining properties. The shear strength of the joint reaches a maximum of 233 MPa when brazed at 1000 degrees C for 10 min. With the brazing temperature increasing, the thickness of the brazing seam increases firstly and then decreases.