Effect of welding temperature on microstructure and mechanical properties of TiAl/Ti 2 AlNb spark plasma diffusion welded joint

The spark plasma diffusion welding of TiAl/Ti 2 AlNb was carried out using pure Ti as an interlayer at 900 °C, 925 °C, and 950 °C under a pressure of 8 MPa for 20 min. The microstructure and element diffusion behavior of the welded joint at different temperatures were investigated, and the tensile strength was tested at room temperature and 650 °C, respectively. The results demonstrated that the microstructure of the joint was TiAl substrate/β-Ti + α 2 -Ti 3 Al/equiaxed α 2 -Ti 3 Al/(β/B 2 ) + acicular α 2 -Ti 3 Al/single B 2 phase, respectively. As the welding temperature increased, the thickness of TiAl diffusion zone and α 2 -Ti 3 Al phase became wider. The tensile strength at room temperature and high temperature decreased with the increase of welding temperature. The increase in the thickness of the brittle α 2 -Ti 3 Al phase was considered to be the main factor leading to the decline of the mechanical properties. The highest tensile strength at room temperature and 650 °C was 679 MPa and 641 MPa, which was 90.9% and 92.2% of that of TiAl base metal, respectively.