Design of TiCx nanoparticles and their morphology manipulating mechanisms by stoichiometric ratios: Experiment and first-principle calculation

The morphology of TiCx nanoparticles is one of the most significant inherent factors that influence their comprehensive performances and extensional applications. However, the design of TiCx nanoparticles and their growth morphologies manipulating in the Al melt are always in challenges, while the stoichiometric ratios controlled synthesis will show a promising prospect. In this study, TiCx ceramic nanoparticles with different stoichiometric ratios (x = 0.5, 0.625, 0.75, 0.875 and 1.0) were fabricated successfully by combustion synthesis in Al-Ti-C reaction system. Based on the evaluation of nanosized TiCx specific exposed planes in the Al melt, the stoichiometric ratios manipulated the Al/TiCx interface performances, including interfacial stability, the nature of bonding and the interface electron transfer were analyzed via first-principle calculation. With the increasing stoichiometric ratios, the TiCx(100) exposed planes in the Al melt gradually stabilized and became exposed, while the TiCx(111) planes showed poor stability and gradually shrank and disappeared. The corresponding morphology will also evolve from octahedron to truncated-octahedron then spheroid with increasing x. Moreover, those interface performances can be selectively controlled by the stoichiometric ratio of TiCx nanoparticles. Finally, morphologies with specific exposed crystal planes in the Al melt can be effectively designed and manipulated for various applications. [Display omitted] •TiCx nanoparticles with specific exposed surfaces were in-situ synthesized controllably in Al melt by combustion synthesis.•TiCx nanoparticles evolved from octahedrons, truncated-octahedrons to spheroids with the increasing of x from 0.5 to 1.0.•The morphology manipulating mechanism of TiCx nanoparticles was revealed by the first principle calculation of the Al/TiCx interface.•With x increasing, TiCx (100) in the Al melt gradually stabilized and exposed while (111) planes shrank and disappeared.