Atomic migration behavior of Ta₄HfC₅-SiBCN ceramics sintered by hot-pressing

Ultra-high temperature ceramics matrix composites have great potential for application in the aerospace. However, the effects of atomic diffusion behavior on the properties are not clear. This work focuses on the diffusion behavior of Ta₄HfC₅-SiBCN multilayer gradient ceramics with meshing structure sintered by hot-pressing sintering. The order of atomic interdiffusion coefficients is Hf> Ta> Si, corresponding to (17.03 ± 8.15), (14.38 ± 5.67) and (10.71 ± 2.88) × 10⁻¹⁸ m²/s, respectively. Moreover, the atomic migration behavior between Ta₄HfC₅ and SiBCN was studied based on first principles. The results show that the vacancy migration energy of Ta atoms in SiC is 0.92 eV, which is greater than that of Hf atoms with 0.18 eV. In addition, Hf atoms promotes vacancy diffusion of Si atoms in the TaC lattice. This work provides data support for the exploration of basic research and diffusion mechanisms.