Green preparation and synthesis mechanism of TiC/Al 3 Ti/Al 2 O 3 composite nanoparticles

In this paper, TiC/Al3Ti/Al2O3 composite nanoparticles were prepared using Ti, Al, and graphite powders, in a NaCl-KCl molten salt medium. The prepared powders were characterised by X-ray diffraction (XRD), scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS), and X-ray photoelectron spectroscopy (XPS). The results showed that the one-step method could only directly generate the AlTi2C phase, but could not generate the TiC/Al3Ti/Al2O3 phase. In the two-step method, the Al, Al3Ti, Al2Ti, and AlTi phases were used as precursors, and then the graphite powder was added. After sintering at 1000°C for 3 h, the TiC/Al3Ti/Al2O3 composite nano-powder was successfully prepared, which can be used as the reinforcement of Al-based composites. During the synthesis process of the TiC/Al3Ti/Al2O3 composite nano-powder, the intermediate AlTi2C phase was generated first, and the exposed [Ti] in the AlTi2C phase adsorbed C to generate the TiC phase. The formation of the TiC phase promoted the decomposition of the AlTi2C phase, resulting in the formation of the Al3Ti phase. Finally, the residual Al phase in the molten salt was oxidised to the Al2O3 phase during the washing process.