Investigation on Ti3AlC2/TiC interfacial properties: Experiment and first-principles calculation

The (Ti3AlC2+Al2O3)(p)/Al3Ti composite was fabricated through hot pressing. The Ti3AlC2(0001)/TiC(111) interface in the (Ti3AlC2+Al2O3)(p)/Al3Ti composite was clearly observed, and its interface properties were conducted using first-principles calculations. The results show that: for the TiC(111) surface, the surface energy of Ti-terminated TiC(111) is lower than that of C-terminated TiC(111), indicating that Ti-terminated TiC(111) is more stable. For the Ti3AlC2(0001) surface, surface energy from high to low is: C-terminated > Ti(Al)-terminated > Ti(C)-terminated > Al-terminated Ti3AlC2(0001) surfaces in environments of Ti-rich and Al-rich, while the stability is opposite. Among the 24 interface models, Ti(Al)-on-top-C1 has the highest work of adhesion (13.1552 J/m(2)) and the lowest interface energy (-3.3553 J/m(2)), indicating the best interface bonding strength and stability. During the relaxation process, the stacking sites of the three interface models, which were named C-hcp-hollow-C2, C-fcc-rollow-C3, and Ti(Al)-on-top-C1, changed. By analyzing the electronic structure of eight interface models, it was found that covalent and metal bonds form at the interface, such as Ti-C covalent bond, Al-C covalent bond, C-C covalent bond, and Ti-Ti metallic bond. This indicates that the type of chemical bonds at the Ti3AlC2(0001)/TiC(111) interface is determined by the TiC(111) surface termination and Ti3AlC2(0001) surface termination. In the first-principles tensile test, the critical strain and ultimate tensile strength of the Ti(Al)-on-top-C1 interface model are 8 % and 23.55 GPa, respectively.