Microstructures and mechanical properties of laser brazed TC4 titanium alloy joint using internal dendrite amorphous alloy as the filler metal

The laser brazing technology for TC4 titanium alloy using a Ti-based amorphous alloy as brazing filler metal was studied. Results show that laser brazing of TC4 titanium alloy can be achieved by using a Ti-based amorphous alloy, and a continuous and stable brazed joint without welding defects can be obtained. The microstructure comprises broken beta-Ti dendrites dispersed on the amorphous alloy matrix, and columnar crystals are formed on both sides near the interface of the base metal. In the brazing process, the Zr element in the liquid filler metal diffuses to the TC4 base metal at a depth of about 50 mu m. The hardness of the brazed zone is about 540 HV, which is much higher than that of the base metal at 320 HV. The tensile strength of brazed joint is about 960 MPa, and the specimen fractured on TC4 base metal.