Size Control of In Situ Synthesized TiB2 Particles in Molten Aluminum

Aluminum-matrix nanocomposites offer advantageous properties over conventional aluminum alloys. However, controlling the size and size distribution of ceramic nanoparticles during in situ synthesis at high temperatures has been a long-term challenge due to a lack of effective size-control mechanisms. Here, we successfully synthesized titanium diboride (TiB2) nanoparticles with an unprecedented narrow size distribution in molten aluminum. The average size of TiB2 nanoparticles was tunable from 22.1 to 171.4 nm by solely controlling the reaction temperature under a diluted reactant salt solution. To uncover the mechanism of particle size control, an interface diffusion-controlled model was developed. The dilution of reactant salt was crucial to achieve a steady reaction environment while confining the growth of the particles in a shallow region. The model suggests that the average size of as-synthesized nanoparticles is mostly controlled by reaction temperature and unaffected by the titanium salt concentration in a diluted solution due to a steady diffusion of titanium and boron. Temperature controls the diffusion of reactants and nucleation rate to dictate the average size of the as-synthesized nanoparticles.

Automated summary

The study successfully synthesized TiB2 nanoparticles with a narrow size distribution in molten aluminum at high temperatures by controlling the reaction temperature, and also developed an interface diffusion-controlled model to reveal the size control mechanism. Temperature plays a crucial role in regulating the average size of synthesized nanoparticles, while the dilution of reactant salt is essential for maintaining a steady reaction environment.