The microstructure and mechanical properties of electron beam welded Ti2AlNb-based alloy joint with the addition of TiB2

In this paper, 5 mm thick Ti-22Al-25Nb alloy plate was used for vacuum electron beam welding. The effect of TiB₂ on the surface forming, macroscopic morphology, microstructure and mechanical properties of the joint was studied by optical microscope, scanning electron microscope and X-ray diffractometer. The results showed that TiB₂ had an obvious effect on the microstructure and mechanical properties. The surface forming of the joint was good with the addition of TiB₂, while the lower surface of the joint without the addition of TiB₂ was discontinuous and presented a droplet state. The phase of WZ with TiB₂ was composed of B2 phase, TiB and a small amount of O phase, while it mainly consisted of B2 phase for the joint without addition of TiB₂. The hardness of the WZ with different addition of TiB₂ was higher than that of the WZ without addition of TiB₂. The breaking strength at high temperature of the joint without addition of TiB₂ was 639 MPa, which was only 72.5 % of the BM and lower than that of the joint with different addition of TiB₂.