Effect of a Cu Interlayer on the Joining of a TiAl-based Alloy and a Ni-based Superalloy by Laser Welding
Z.Y. Xiao, X.L. Cai, H.Y. Zhao, K.Y. Wang, X.Y. Gu and H.M. Li
Dissimilar welding of TiAl-based alloy to Ni-based superalloy with a Cu interlayer was performed by laser welding. Detailed effects of interlayer thickness on microstructural characterization and mechanical properties of the joints were investigated. The results indicated that the thickness of the Cu interlayer had a great influence on the joint performance. Laser welding cannot be achieved by using 0.2 mm Cu interlayer due to the main brittle phases such as AlNi2Ti, Ni0.35Al0.30Ti0.35, etc. formed in the joint. With the Cu interlayer thickness increased to 0.4 and 0.6 mm joints with no macrocracks were achieved. The (Cu,Ni) solid solution, Cr solid solution, Al(Cu,Ni)2Ti/(Cu,Ni) eutectic structure and Al(Ni,Cu)2Ti formed in the laser welds with Cu interlayers of 0.4 and 0.6 mm thickness which reduced the hardness. The average tensile strength of the laser welded joints with Cu interlayers of 0.4 and 0.6 mm thickness were 158 MPa and 88 MPa, respectively. The weak links of the joints were the TiAl/weld interface. The temperature field and stress field simulation of laser welding with different thickness of Cu interlayer has been analysed and detailed.
Keywords: Nd:YAG laser, TiAl-based alloy, Ni-based superalloy, Cu interlayer, laser welding, dissimilar materials, microstructure, phase, numerical simulation, finite element analysis (FEA)