Design of Gr/2024Al composite and Ti6Al4V titanium alloy joint brazed using AgCuSnTi filler and Ni/Nb/Ni composite interlayers

The AgCuSnTi filler was designed to braze Gr/2024Al composite and Ti6Al4V titanium alloy through investigating the effect of Sn and Ti addition in AgCuSnTi filler on the microstructure and mechanical property of the joint. The results showed that Sn and Ti addition decided the distribution of compounds (Al₂Cu and Al₅CuTi₂ phases) in the brazing seam. The increasing of Sn content could enhance the flowability of brazing alloy, and promote the compounds to be dispersive in the brazing seam. Ti in the filler induced the formation of Al₅CuTi₂ phase instead of Al₂Cu phase. When the Gr/2024Al and Ti6Al4V were brazed using the AgCuSnTi filler with 3 wt.% Ti and 27 wt.%Sn at 680℃ for 10 min, the Al₂Cu and Al₅CuTi₂ phases were dispersed in the brazing seam. The maximum shear strength of the brazed joint was 17 MPa and cracks propagated in the Gr/2024Al substrate. In addition, Ni/Nb/Ni composite interlayers were designed to strengthen the Gr/2024Al composite and Ti6Al4V titanium alloy joint, and the joint strength increased to 24 MPa owing to the adoption of the interlayers.