Microstructure characterization and mechanical properties of (TiC–TiB2)–Ni/TiAl/Ti functionally gradient materials prepared by FAPAS

• The synthesis of (TiC–TiB2)–Ni and bonding to Ti were simultaneously accomplished.
• Higher pressure led to smaller TiC and TiB2 particles.
• Shear experiments showed that fracture occurred on (TiC–TiB2)–Ni and TiAl interface.
• The lubrication films formed at elevated temperature resulted in a smaller mass loss.

The composite ceramics TiC–TiB2 with Ni as the binder were successfully fabricated and bonded with Ti using TiAl as the transitional layer. (TiC–TiB2)–Ni composite ceramics were prepared in-situ through the combustion synthesis process using titanium, nickel and B4C powders as raw materials. Interfacial investigations of (TiC–TiB2)–Ni/TiAl and TiAl/Ti showed that the three layers were bonded together very well. The TiC and TiB2 particles of the synthesized composite ceramics were fine and homogeneously dispersed in the matrix. The shear strength increased as the applied current and pressure increased, with the maximum shear strength of the joint reaching 85.78 MPa. The fracture morphology investigated by SEM indicated that the fracture occurred in the (TiC–TiB2)–Ni/TiAl interface. The friction coefficient and the loss rate of the ceramic (TiC–TiB2)–Ni decreased as the testing temperature increased. The lubrication films of Fe2O3, TiO2, and B2O3 formed at an elevated temperature resulted in a smaller mass loss and friction coefficient.