Evaluation on diffusion bonded joints of TiAl alloy to Ti_3SiC_2 ceramic with and without Ni interlayer: Interfacial microstructure and mechanical properties

摘要

Diffusion bonding of TiAl alloys and Ti_3SiC_2 ceramics were carried out in a vacuum atmosphere. The microstructures and mechanical properties of the bonded joints were investigated. Results showed that three coherent intermetallic layers formed in the TiAl/Ti_3SiC_2 joints during bonding process. The compound layer adjacent to Ti_3SiC_2 substrate was indicated to be Ti_sSi_3, in which brittle fracture of the joints took place during shear strength test. The properties of diffusion bonded joints were greatly improved attributed to the formation of a good transition in the joint as well as the relief of the residual stress when using Ni foil as interlayer. Formation mechanisms of the compound layers during bonding process were discussed. Shear test results showed that the maximum shear strength reached 52.3 MPa. Corresponding fractograph indicated that the crack mainly propagated along Ti_3SiC_2 substrate adjacent to the bonding zone, accompanied with an intergranular and transgranular fracture mode.